NOAA's National Centers for Environmental Information
Issued 13 October 2023
Please note that the values presented in this report are based on preliminary data. They will change when the final data are processed, but will not be replaced on these pages.
National Drought Highlights
- Based on the Palmer Drought Index, severe to extreme drought affected about 19% of the contiguous United States as of the end of September 2023, about the same as last month. About 12% of the contiguous U.S. fell in the severely to extremely wet categories.
- About 33% of the contiguous U.S. fell in the moderate to extreme drought categories (based on the Palmer Drought Index) at the end of September.
- On a broad scale, the 1980s and 1990s were characterized by unusual wetness with short periods of extensive droughts, the 1930s and 1950s were characterized by prolonged periods of extensive droughts with little wetness, and the first two decades of the 2000s saw extensive drought and extensive wetness (moderate to extreme drought graphic, severe to extreme drought graphic).
- A file containing the national monthly percent area severely dry and wet from 1900 to present is available for the severe to extreme and moderate to extreme categories.
- Historical temperature, precipitation, and Palmer drought data from 1895 to present for climate divisions, states, and regions in the contiguous U.S. are available at the Climate Division: Temperature-Precipitation-Drought Data page. These filenames begin with "climdiv".
- According to the weekly U.S. Drought Monitor (USDM), as of October 3, 2023, 40.06% of the contiguous U.S. (CONUS) (33.62% of the U.S. including Alaska, Hawaii, and Puerto Rico) was classified as experiencing moderate to exceptional (D1-D4) drought.
Detailed Drought Overview
The upper-level atmospheric circulation over North America during September 2023 consisted of a battle between a high pressure ridge from the south and Pacific weather systems moving in the jet-stream flow across the northern states, with some tropical weather systems thrown into the mix. The ridge was connected to the subtropical high pressure belt that stretches from the Atlantic Ocean (Bermuda High) to the Pacific Ocean (North Pacific High). The ridge was mostly anchored over the Southwest to southern Plains with an extension into the Upper Midwest, but it wobbled across the CONUS depending on the movement of the Pacific weather systems. The ridge was responsible for the warmer-than-normal monthly temperatures that stretched from the southern Plains to northern Plains and western Great Lakes, as well as over New England. It also inhibited precipitation across much of the Great Plains to East Coast. The Pacific weather systems (shortwave troughs and closed lows) dragged cold fronts and surface lows with them that brought above-normal precipitation and cooler-than-normal temperatures to much of the West. Above-normal precipitation extended into parts of the Plains and Upper Midwest, but the weather systems were weakened by the ridge as they moved east with the result being only scattered areas of above-normal precipitation from the Mississippi River to East Coast. Precipitation in the East was supplemented by Hurricane Lee, which brought rain to New England at mid-month, and Tropical Storm Ophelia, which soaked coastal areas of the Mid-Atlantic before its remnants brought rain to the coastal Northeast during the last half of the month. While the Southeast was still drier than normal for the month, in spite of the fronts and being sideswiped by Ophelia, these systems did bring the region a near- to cooler-than-normal month. The subtropical ridge system extended westward to Hawaii, which had a drier-than-normal month, and eastward to the Caribbean, where Puerto Rico and the U.S. Virgin Islands were both drier and warmer than normal for September.
The drier- and warmer-than-normal weather contributed to numerous wildfires across the West and South (wildfire maps for September 1, 22, 30, legend-1, legend-2) — especially in the Southwest, where the month has been dry, and coastal parts of the Northwest, where September had been dry until the last week when an atmospheric river soaked coastal areas. In spite of the near-average number of fires, the total acreage burned for the year-to-date is still below the ten-year average, nationally. The above-normal temperatures increased evapotranspiration (EDDI), especially in the Southwest, southern Plains, and Midwest, further drying soils where it didn't rain (USDA topsoil percentages, USDA subsoil percentages, CropCASMA topsoil, CropCASMA subsoil, GRACE root zone, GRACE surface soil moisture, CPC model, NLDAS model, VIC model, QuickDRI, SPoRT layer 1, SPoRT layer 2, SPoRT layer 3, SPoRT layer 4) and desiccating vegetation (VHI, stressed vegetation, VegDRI). Streamflow and groundwater (USGS well observations, GRACE satellite estimations) were also low in these areas. These conditions were not limited to the U.S. The ridge affected much of North America, with wildfires, desiccated vegetation, and low groundwater and soil moisture extending across much of Canada and Mexico.
The above-normal precipitation in September resulted in contraction or reduction of the intensity of drought over parts of the Plains, Upper Midwest, and Mid-Atlantic Coast. Drought or abnormal dryness intensified or expanded across the Ohio Valley to Gulf of Mexico Coast, and in parts of Hawaii, Puerto Rico, the Pacific Northwest, Southwest, Great Plains, and Upper Midwest. Drought expansion exceeded contraction with the USDM-based national moderate-to-exceptional drought footprint across the CONUS increasing from 34.3% at the end of August to 40.1% at the end of September (from 28.8% to 33.6% for the 50 states and Puerto Rico).
According to the Palmer Drought Index, which goes back to the beginning of the 20th century, about 33.3% of the CONUS was in moderate to extreme drought at the end of September, which is an increase compared to the end of August.
Drought conditions at the end of September, as depicted on the October 3, 2023 USDM map, included the following core drought and abnormally dry areas:
- Areas of moderate (D1) to extreme (D3) drought continued across parts of the West, basically the opposite ends — the Pacific Northwest and the Southwest (Four Corners states) — with exceptional drought (D4) developing in New Mexico. The percent area of the Western U.S. experiencing moderate to exceptional drought, according to USDM statistics, rose from 30.8% at the end of August to 31.6% at the end of September. Drought contracted or reduced in intensity in Montana and parts of Oregon and Utah, but intensified or expanded in the other parts of the Pacific Northwest and in the Southwest. Based on the Palmer Drought Index, the drought area across the West as a whole increased from 22.1% at the end of August to 25.9% at the end of September.
- Beneficial precipitation fell in northern and western parts of the Great Plains in September. The month was warmer than normal in the central to northern Plains, where moderate to exceptional drought continued. Beneficial rain contracted drought in parts of the southern Plains, but the region was hot and areas with little precipitation this month had drought expand or intensify, with moderate to exceptional drought continuing. In the central to northern Plains, the moderate to exceptional drought area fell slightly from 28.2% of the region at the end of August to 27.5% of the region at the end of September. In the southern Plains, the moderate to exceptional drought area continued its rise from 70.6% at the end of August to 74.0% at the end of September. In the Lower Mississippi River Valley, the drought area continued its streak upward, going from 46.1% at the end of August to 69.7% at the end of September. Drought and abnormal dryness exploded across Tennessee, covering 79.1% of the state (15.8% in moderate drought) by the end of September. Taken together, the southern Plains, Lower Mississippi Valley, and Tennessee (South Region) saw moderate to exceptional drought rise from 56.3% at the end of August to 68.6% at the end of September.
- Beneficial rains fell in northwestern parts of the Midwest, contracting drought and abnormal dryness, but other areas continued dry and drought intensified or expanded there. Regionwide, the Midwest region's drought area expanded from 41.1% at the end of August to 56.0% at the end of September. The most extreme drought areas (moderate to extreme drought) were in Missouri, Iowa, Wisconsin, and Minnesota, with exceptional drought in Iowa.
- Drought made inroads in the Southeast, especially in Alabama and the Florida panhandle, and continued in the western Florida peninsula, northern and western Virginia, and the Carolinas. The region's moderate to extreme drought area doubled from 11.0% at the end of August to 23.1% at the end of September.
- Patches of moderate or severe drought exist in western and southern parts of the Northeast, with the drought area increasing slightly from 2.3% at the end of August to 2.4% at the end of September.
- In Hawaii, extreme drought developed on Maui, with the total drought area growing from 60.8% at the end of August to 79.4% at the end of September.
- Moderate drought continued in northwest Puerto Rico and developed in the northeast, with the drought area increasing from 8.3% at the end of August to 13.7% at the end of September. In the U.S. Virgin Islands, extreme drought worsened to exceptional drought on St. Croix and St. Thomas, and moderate drought intensified to severe drought on St. John.
- In Alaska, abnormal dryness shrank to cover 1.1% of the state.
- In the U.S.-Affiliated Pacific Islands, moderate drought continued at Tutuila in American Samoa, moderate drought improved to abnormal dryness at Wotje in the Marshall Islands, and abnormal dryness ended at Pingelap (Federated States of Micronesia), while abnormal dryness continued at Kwajalein and developed at Ailinglaplap and Majuro (Marshall Islands).
Palmer Drought Index
The Palmer drought indices measure the balance between moisture demand (evapotranspiration driven by temperature) and moisture supply (precipitation). The Palmer Z Index depicts moisture conditions for the current month, while the Palmer Hydrological Drought Index (PHDI) and Palmer Drought Severity Index (PDSI) depict the current month's cumulative moisture conditions integrated over the last several months.
While both the PDSI and PHDI indices show long-term moisture conditions, the PDSI depicts meteorological drought while the PHDI depicts hydrological drought. The PDSI map may show less severe and extensive drought (as well as wet spell conditions) in some parts of the country than the PHDI map because the meteorological conditions that produce drought and wet spell conditions are not as long-lasting as the hydrological impacts.
Used together, the Palmer Z Index and PHDI maps show that short-term drought occurred from the Great Lakes and Upper Mississippi Valley to the Gulf of Mexico Coast, and in parts of the Southwest, expanding or intensifying long-term drought and reducing areas of long-term wet conditions (PHDI maps for September compared to August). Short-term wet conditions occurred in parts of the interior West, northern Plains, and coastal Northeast, maintaining or expanding long-term wet conditions.
Standardized Precipitation Index
The Standardized Precipitation Index (SPI) measures moisture supply. The SPI maps here show the spatial extent of anomalously wet and dry areas at time scales ranging from 1 month to 24 months.
The SPI maps illustrate how moisture conditions have varied considerably through time and space over the last two years. Dryness is evident across parts to most of the Southwest and southern Plains to central Gulf of Mexico Coast at all time scales, especially 1-6 and 24 months. Parts to most of the Upper Mississippi Valley are dry at all time scales, especially 2-12 months. Parts of the central Plains are dry at 1-2 and 6-24 months, especially at the longer time scales. Parts to most of the Ohio Valley are dry at 1-2 months, 6, and 12 months. Dryness can be seen across parts of the Pacific Northwest at 6 to 12 months, parts of the northern Plains at 3 to 12 months, and in parts of the Mid-Atlantic to central Appalachians at 6- to 24-month time scales. Much of the West and much of the Northeast are wet at all time scales; western parts of the Great Plains are wet at 1- to 12-month time scales with northern parts of the Plains wet at 24 months; and wet conditions cover parts of the Mid- to Lower Mississippi Valley at 3, 9, and 12 months.
Standardized Precipitation Evapotranspiration Index
The SPI measures water supply (precipitation), while the SPEI (Standardized Precipitation Evapotranspiration Index) measures the combination of water supply (precipitation) and water demand (evapotranspiration as computed from temperature). Warmer temperatures tend to increase evapotranspiration, which generally makes droughts more intense.
For the Northern Hemisphere, September marks the beginning of climatological autumn, which is the season when a lower sun angle results in decreasing evapotranspiration. During September 2023, temperatures were still warmer than normal from the Rockies to Mississippi Valley and much of the Northeast, with record warm temperatures occurring in the Southwest, along the Gulf of Mexico Coast, and in the Upper Mississippi Valley. Much of the region from the Great Lakes to Gulf Coast was drier than normal, with record dryness occurring locally in the southern Great Lakes. The combination of increased evapotranspiration due to the abnormally warm temperatures, and lack of precipitation, resulted in more severe SPEI values than SPI values in the South and a few parts of the Great Lakes during September. The combination of low precipitation and above-normal temperatures over the last several months (precipitation anomaly maps for the last 1, 2, 3, 4, 6, 9, 12 months) (temperature anomaly maps for the last 1, 2, 3, 4, 9, 12 months) continued the pattern of more extreme SPEI than SPI in these regions, as well as in the Southwest and Pacific Northwest (SPEI maps for the last 1, 2, 3, 5, 6, 9, 12 months) (SPI maps for the last 1, 2, 3, 5, 6, 9, 12 months).
The last 2 to 3 years have been extremely dry in the central Plains — so dry, in fact, that the SPI is more extreme than the corresponding SPEI in spite of temperatures being above normal — but in the southern Plains the heat dominated the dryness, so the SPEI is more extreme than the SPI there (24-month SPEI, SPI) (36-month SPEI, SPI). For the western U.S., the last 12 months have seen temperatures that were near the long-term average, but most of the last 10 to 20 years have been a period of unusually warm temperatures across the West. There have also been periods of extreme dryness westwide during this period (this year being an exception). The combination of excessive heat and dryness has resulted in more extreme SPEI values than SPI values in parts of the West for the last 2 to 6 years (SPEI maps for last 24, 36, 48, 60, 72 months) (SPI maps for last 24, 36, 48, 60, 72 months).
The SPEI at the 1- to 5-month time scales was more extreme than the SPI for Louisiana, Texas, Arizona, and New Mexico. In some cases, the SPEI was record dry whereas the SPI was not:
- August-September SPEI for Louisiana vs. August-September SPI. The SPEI was record dry, while the SPI ranked second driest.
- July-September SPEI for Louisiana vs. July-September SPI. The SPEI was record dry, while the SPI ranked second driest.
- May-September SPEI for Louisiana vs. May-September SPI. The SPEI was record dry, while the SPI tied as second driest.
- July-September SPEI for New Mexico vs. July-September SPI. The SPEI was record dry, while the SPI was in the top 10 driest category.
- July-September SPEI for Arizona vs. July-September SPI. The SPEI was second driest, while the SPI was in the top 20 driest category.
- July-September SPEI for Texas vs. July-September SPI. The SPEI was third driest, while the SPI was in the top 20 driest category.
Regional Discussion
Upper Mississippi River Basin
September 2023 was drier than normal over parts of the Upper Mississippi River Valley and wetter than normal over other parts. But drier-than-normal conditions dominated for much of the last 12 months. The basin had the fifth driest April-September and 23rd driest October-September in the 1895-2023 record. According to the Palmer Drought Index, 64.4% of the basin was in moderate to extreme drought at the end of September; this is more than the end of August. Based on the USDM, 73.0% of the basin was in moderate to exceptional drought, which is more than last month.
Ohio River Basin
September was much drier than normal over the Ohio River Valley, with some parts record dry. Drier-than-normal conditions dominated for much of the last six months. The basin had the eleventh driest September and 29th driest April-September in the 129-year record. The dryness and heat have not been persistent and severe enough over time to register on the Palmer Drought Index, with only 2% of the basin in moderate drought at the end of September. But based on the USDM, 30.5% of the basin was in moderate drought, which is more than last month.
Rio Grande River Basin
The Rio Grande River Basin has been unusually dry and hot this year. The basin had the third driest July-September and June-September, and 17th driest October-September, on record. Each of the multi-month periods for the last five months (May-September, June-September, July-September, August-September), including September, have been record warm. Almost the entire basin (96.1%) was in moderate to extreme drought, based on the Palmer Drought Index, at the end of September, which is slightly more than last month. According to the USDM, 93.7% of the basin was in moderate to exceptional drought, which is more than last month. Both the PDSI and USDM show that the Rio Grande Basin has been in cyclical drought for the last 23 years. The Palmer Drought Index reveals that the basin has experienced frequent drought for the last 123 years.
Hawaii
Drier-than-normal conditions dominated most of the stations across the main Hawaiian Islands during September 2023, August-September, July-September, and June-September. The last 6 to 12 months were mostly wetter than normal, except for the windward side of the Big Island and parts of Oahu and Maui. At longer time scales, Oahu was mostly drier than normal with the windward sides of the other islands drier than normal and leeward sides wetter than normal (precipitation anomaly maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months) (climate engine model percent of normal precipitation map for the last month).
Monthly streamflow was mostly below normal. Based on satellite analyses (stressed vegetation, drought stress, VHI), there were areas of vegetative stress this month across the islands, but especially on Oahu, Molokai, Maui, and the Big Island.
Drought expanded across Hawaii during September, with extreme drought developing on Maui. The moderate to extreme drought area increased from 60.8% of the state on August 29 to 79.4% of the state on the October 3, 2023 USDM map.
Alaska
September was drier than normal across much of the Aleutians to Cook Inlet and some stations in the north and southeast interior. The last 2 to 4 months saw dry conditions at locations in the east-central interior and southern panhandle regions. Alaska had a generally mixed precipitation anomaly pattern at the 5- to 12-month periods, except for dryness over the Aleutians and Northwest Gulf. Dryness was consistent in parts of the southern coast at longer time scales (low elevation station precipitation anomaly maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months) (high elevation SNOTEL station precipitation percentile maps for the last 1, 5, and 12 months) (SNOTEL basin and station percent of normal precipitation maps for the last 1, 5, and 12 months) (climate division precipitation rank maps for the last 1, 3, 6, 9, and 12 months) (climate engine model percent of normal precipitation map for the last month) (Leaky Bucket model precipitation percentile map).
September 2023 temperatures were warmer than normal in the panhandle, northern shore, and parts of the Aleutians, and near to colder than normal in the interior to western and southern coastal areas. Warmer-than-normal temperatures dominated at the 2- to 12-month time scales from the panhandle to North Slope, with near- to cooler-than-normal temperatures in the southwest. Colder-than-normal temperatures dominated in the west and interior regions, with above-normal temperatures in the east, north, and southeast, at 9 to 12 months when compared to more recent (1991-2020) normals. But when compared to the long-term (1926-2022) average, temperatures were near average in the west at 9 months and mostly warmer than average at 12 months. This is due to a pronounced warming trend in recent decades (low elevation station temperature anomaly maps for the last 1, 2, 3, 4, 9, 12 months) (climate division temperature rank maps for the last 1, 3, 6, 9, and 12 months) (gridded temperature percentile maps for the last 1, 3, and 9 months) (Leaky Bucket model temperature percentile map).
Monthly streamflow was mostly near to above normal with some low streams in the southwest. Satellite observations of vegetative health (stressed vegetation, drought stress, VHI) revealed some areas of minor stress in the northeast. Satellite-based observations of groundwater and soil moisture (GRACE root zone, GRACE surface, Leaky Bucket modeled soil moisture, SPoRT model soil moisture at shallow [0-10 cm, 10-40 cm] and deeper [40-100 cm, 100-200 cm] layers) suggested some dryness was occurring in the south, north, and east.
The remaining spot of abnormal dryness shrank to about 1.1% of the state on the October 3, 2023 USDM map.
Puerto Rico and U.S. Virgin Islands
September 2023 continued a drier-than-normal pattern across the U.S. Virgin Islands (USVI) and most of Puerto Rico (PR) that has lasted for much of the past year. The last 2-12 months were generally drier than normal in northern and central portions of PR and wetter than normal in the south. The USVI were generally drier than normal for the last 2-12 months. Drier-than-normal conditions dominated at longer time scales and became progressively more widespread (radar-based precipitation anomaly estimates for the last 1, 2, 3, 6, and 9 months) (low elevation station precipitation anomaly maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months) (climate engine model percent of normal precipitation map for the last month: PR and USVI, Caribbean and Gulf of Mexico region).
In a 64-year record, Rohlsen Airport on St. Croix had the driest December-September and July-September, and the second driest January-September, June-September, and September. In a 59-year record, King Airport on St. Thomas had the driest December-September. In all of these rankings, years with too many days missing were excluded. In a 125-year record, June-September 2023 was the eleventh driest June-September for the San Juan area.
Temperatures were consistently warmer than normal, especially for the last 1 to 5 months (low elevation station temperature anomaly maps for the last 1, 2, 3, 4, 9, 12 months). San Juan had the hottest September, June-September, and May-September in the 1899-2023 record. Rohlsen Airport had the hottest September and June-September. King Airport recorded the third warmest September. The excessive heat increased evapotranspiration which made the dry conditions worse.
Root zone analyses indicated that soil conditions were moist across eastern coastal and portions of western PR, but dry along the southern and northern coasts and eastern interior region (root zone soil saturation fraction). Satellite observations of vegetative health (stressed vegetation for PR and USVI, drought stress for PR and USVI, VHI for PR and USVI) revealed areas of drought-related stress. Monthly streamflow on PR showed below-normal streams in western and eastern areas. In the USVI, the groundwater level generally declined during September at St. Croix, St. John, and St. Thomas. For the most part, groundwater levels have been declining since the beginning of the year. The end-of-September groundwater level was well into the bottom third of the historical record on St. Croix and St. John, and mid-range on St. Thomas.
As reported by NIDIS (National Integrated Drought Information System), the increasingly dry conditions on PR are reducing soil moisture and negatively impacting vegetation, with signs of distress across the territory. Some areas have experienced dried or burned vegetation and forage, and some farmers have experienced smaller batches of harvests. Drought continues to be a growing concern for many farmers and residents on the USVI. Soil and vegetation in the USVI are visibly showing signs of distress such as decreased soil moisture, and both livestock and poultry have been negatively impacted by the dry and hot conditions. Precautions such as ordering hay and water deliveries are being taken in some areas. Farmers in St. Thomas reported that ponds were evaporating due to the high heat and high winds have reduced soil moisture. High winds, excessive heat, and dry conditions continue to reduce soil moisture on St. John. Although sporadic rain has occurred, farmers on St. Croix are reporting that it is not penetrating the soil due to evaporation from high winds.
In the USVI, extreme drought worsened to exceptional drought on St. Croix and St. Thomas, and moderate drought worsened to severe drought on St. John. Moderate drought expanded on PR, with the drought area increasing to cover about 13.7% of the island on the October 3, 2023 USDM map.
CONUS State Precipitation Ranks
September 2023 was drier than normal across the Great Lakes to Gulf of Mexico Coast, much of the Southeast, and parts of the central to southern Plains and Southwest, with record dryness occurring in parts of the Great Lakes. Fifteen states had a precipitation rank in the driest third of the 129-year historical record for September, including three that ranked in the top ten driest category — Ohio (fifth driest), Michigan (ninth driest), and Indiana (tenth driest) — and two that were close: Mississippi and Tennessee (both 13th driest).
July-September 2023 was drier than normal across the Southwest to Gulf of Mexico Coast, much of the Upper Mississippi Valley, and parts of the Southeast and Great Plains, with record dryness occurring locally in the Southwest to Gulf Coast. Eleven states had a precipitation rank in the driest third of the 1895-2023 historical record for July-September, including four that ranked in the top ten driest category — Louisiana (second driest), Texas (seventh driest), and Mississippi and New Mexico (both eighth driest).
April-September 2023 was drier than normal across the Southwest to Gulf of Mexico Coast, much of the Mississippi and Ohio Valleys and Great Lakes, and parts of the Plains, Far West, and Appalachians. Thirteen states had a precipitation rank in the driest third of the historical record for April-September, including four that ranked in the top ten driest category — Iowa (second driest), Louisiana (sixth driest), Arizona (seventh driest), and Minnesota (tenth driest) — and two that were close: Missouri and Wisconsin (both eleventh driest).
The year to date (January-September 2023) was drier than normal across the Southwest to Gulf of Mexico Coast, much of the Mississippi and Ohio Valleys and Great Lakes, and parts of the Plains, Pacific Northwest, and Mid-Atlantic, with record dryness occurring locally in the Gulf Coast. Twelve states had a precipitation rank in the driest third of the historical record for January-September, including one that ranked in the top ten driest category — Iowa (tenth driest).
The last 12 months (October 2022-September 2023) were drier than normal across the Southwest to Gulf of Mexico Coast, much of the Mississippi and Ohio Valleys and Great Lakes, and parts of the Plains, Pacific Northwest, and Mid-Atlantic. Sixteen states had a precipitation rank in the driest third of the historical record for October-September, including one that ranked in the top ten driest category — Iowa (eighth driest).
Agricultural Belts
During September 2023, the Primary Corn and Soybean agricultural belt was mostly drier than normal, with warmer-than-normal conditions in northwest portions and near- to cooler-than-normal conditions in the south. The month ranked as the tenth driest and 18th warmest September, regionwide, in the 1895-2023 record.
March marks the beginning of the growing season for the Primary Corn and Soybean agricultural belt. March-September 2023 was mostly near to warmer than average and near to drier than average. The period ranked as the 16th driest and 31st warmest March-September, regionwide.
The period April-June was especially dry for the Primary Corn and Soybean belt with temperatures mostly near to warmer than normal. Beneficial precipitation in eastern and southern parts occurred in July and August, but dry conditions in September increased the overall longer-term (April-September) moisture deficits. April-September 2023 ranked as the tenth driest and 28th warmest April-September, regionwide.
According to the U.S. Department of Agriculture (USDA), as of October 3, 2023, drought affected approximately 34% of barley production, 59% of corn production, 43% of cotton production, 52% of sorghum production, 58% of soybean production, 51% of spring wheat production, 49% of winter wheat production, 41% of hay acreage, 47% of the cattle inventory, 36% of the milk cow inventory, and 39% of the sheep inventory. Based on October 1 USDA statistics, 18% of the nation's corn crop, 17% of the soybean crop, 43% of the cotton crop, and 35% of the nation's pasture and rangeland were in poor to very poor condition, and 55% of the nation's topsoil and 60% of the subsoil were short or very short of moisture (dry or very dry). The table below lists the end-of-September soil moisture, pasture and rangeland, corn, soybean, and cotton condition by state, with those states having 30 percent or more of topsoil or subsoil moisture short or very short, or 30 percent or more of the crop or pasture and rangeland in poor or very poor condition, highlighted in yellow:
U.S.-Affiliated Pacific Islands
The NOAA National Weather Service (NWS) offices, the Pacific ENSO Applications Climate Center (PEAC), and partners provided reports on conditions across the Pacific Islands.
In the U.S. Affiliated Pacific Islands (USAPI) (maps — Federated States of Micronesia [FSM], Northern Mariana Islands, Marshall Islands [RMI], Republic of Palau [ROP], American Samoa, basinwide), September 2023 was drier than normal in the Marshall Islands, Guam, and Yap in the FSM, but near to wetter than normal in most other areas.
Monthly precipitation amounts were below the monthly minimum needed to meet most water needs (4 inches in the Marianas and Pago Pago, and 8 inches elsewhere) in the Marshalls (Ailinglaplap, Kwajalein, Majuro, and Wotje). September precipitation was above the monthly minimums at the rest of the stations across the USAPI. The 4- and 8-inch thresholds are important because, if monthly precipitation falls below the threshold, then water shortages or drought become a concern.
The tropical Pacific climatology can experience extremes in precipitation, from very low precipitation during the dry season to very high precipitation during the wet season. This can result in monthly normal precipitation values that are different from the monthly minimum needed to meet most water needs, and this can lead to percent of normal values that seem odd. This was the case during September 2023, which is in the wet season for most of Micronesia, and in the dry season for American Samoa, Kosrae, Pohnpei, and Kapingamarangi.
Precipitation was above the monthly minimum but below normal (1981-2010 normal), because the normals are high, at:
- Yap: September 2023 precipitation 9.46 inches, September normal mean 13.76 inches, September normal median 13.50 inches.
- Ulithi: September 2023 precipitation 8.55 inches, September normal mean 11.70 inches.
- Rota: September 2023 precipitation 11.82 inches, September normal mean 15.04 inches.
- Pingelap: September 2023 precipitation 13.74 inches, September normal mean 14.24 inches.
- Jaluit: September 2023 precipitation 9.31 inches, September normal mean 11.25 inches.
In the table below, the station identified as Koror is Palau International Airport (Airai).
| Station Name | Oct 2022 | Nov 2022 | Dec 2022 | Jan 2023 | Feb 2023 | Mar 2023 | Apr 2023 | May 2023 | Jun 2023 | Jul 2023 | Aug 2023 | Sep 2023 | Oct- Sep |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chuuk | 124% | 93% | 116% | 92% | 215% | 85% | 137% | 191% | 118% | 130% | 118% | 112% | 121% |
| Guam NAS | 150% | 77% | 182% | 350% | 188% | 263% | 198% | 916% | 146% | 86% | 132% | 98% | 144% |
| Kapingamarangi | 34% | 55% | 53% | 166% | 47% | 116% | 141% | 137% | 145% | 162% | 121% | 256% | 110% |
| Koror | 241% | 88% | 105% | 187% | 102% | 185% | 77% | 165% | 77% | 145% | 125% | 130% | 124% |
| Kosrae | 169% | 107% | 99% | 131% | 188% | 67% | 120% | 87% | 166% | 132% | 104% | 123% | 102% |
| Kwajalein | 161% | 81% | 88% | 224% | 50% | 189% | 188% | 345% | 143% | 45% | 81% | 61% | 119% |
| Lukonor | 95% | 94% | 54% | 124% | 68% | 96% | 77% | 61% | 116% | 75% | 74% | 115% | 75% |
| Majuro | 147% | 91% | 90% | 157% | 138% | 169% | 151% | 102% | 105% | 70% | 95% | 56% | 108% |
| Pago Pago | 149% | 118% | 71% | 114% | 110% | 106% | 152% | 168% | 109% | 102% | 42% | 156% | 103% |
| Pohnpei | 148% | 85% | 74% | 136% | 146% | 109% | 141% | 145% | 121% | 148% | 219% | 156% | 131% |
| Saipan | 151% | 60% | 130% | 441% | 118% | 138% | 192% | 225% | 92% | 46% | 142% | 109% | 126% |
| Yap | 217% | 68% | 131% | 133% | 118% | 137% | 104% | 131% | 121% | 168% | 145% | 70% | 126% |
| Station Name | Oct 2022 | Nov 2022 | Dec 2022 | Jan 2023 | Feb 2023 | Mar 2023 | Apr 2023 | May 2023 | Jun 2023 | Jul 2023 | Aug 2023 | Sep 2023 | Oct- Sep |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chuuk | 14.27" | 9.83" | 13.00" | 9.34" | 15.60" | 7.09" | 17.14" | 21.57" | 13.73" | 15.56" | 15.23" | 13.07" | 165.43" |
| Guam NAS | 17.12" | 5.66" | 9.32" | 14.02" | 5.69" | 5.45" | 5.01" | 31.15" | 9.00" | 8.69" | 19.47" | 12.46" | 143.04" |
| Kapingamarangi | 2.76" | 5.11" | 5.23" | 15.23" | 4.37" | 13.24" | 19.19" | 16.59" | 20.04" | 22.86" | 9.87" | 25.45" | 159.94" |
| Koror | 28.49" | 10.00" | 11.76" | 19.04" | 8.74" | 13.74" | 5.60" | 19.53" | 13.44" | 26.81" | 16.86" | 15.26" | 189.27" |
| Kosrae | 18.53" | 14.74" | 15.95" | 21.87" | 24.25" | 10.81" | 21.08" | 15.41" | 24.30" | 19.67" | 14.72" | 17.52" | 218.85" |
| Kwajalein | 18.02" | 9.09" | 5.88" | 7.08" | 1.32" | 4.43" | 9.87" | 23.18" | 9.93" | 4.45" | 7.86" | 6.60" | 107.71" |
| Lukonor | 10.73" | 8.52" | 6.06" | 10.45" | 6.08" | 8.92" | 8.68" | 7.13" | 13.55" | 11.89" | 10.33" | 11.63" | 113.97" |
| Majuro | 18.76" | 12.21" | 10.30" | 12.14" | 9.51" | 11.12" | 14.23" | 10.35" | 11.56" | 7.87" | 11.07" | 6.27" | 135.39" |
| Pago Pago | 13.82" | 11.93" | 9.10" | 15.19" | 13.19" | 11.34" | 14.25" | 16.19" | 5.81" | 5.64" | 2.26" | 10.18" | 128.9" |
| Pohnpei | 22.62" | 12.66" | 11.86" | 17.94" | 13.99" | 14.29" | 25.90" | 29.02" | 17.94" | 22.76" | 31.21" | 19.57" | 239.76" |
| Saipan | 16.07" | 3.39" | 5.01" | 11.16" | 3.05" | 2.61" | 5.05" | 5.35" | 3.34" | 4.13" | 18.62" | 11.03" | 88.81" |
| Yap | 26.48" | 5.99" | 11.17" | 8.51" | 6.11" | 6.26" | 5.86" | 10.28" | 14.59" | 25.35" | 21.43" | 9.46" | 151.49" |
| Station Name | Oct 2022 | Nov 2022 | Dec 2022 | Jan 2023 | Feb 2023 | Mar 2023 | Apr 2023 | May 2023 | Jun 2023 | Jul 2023 | Aug 2023 | Sep 2023 | Oct- Sep |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chuuk | 11.51" | 10.61" | 11.25" | 10.10" | 7.25" | 8.32" | 12.47" | 11.30" | 11.66" | 11.98" | 12.86" | 11.71" | 136.77" |
| Guam NAS | 11.44" | 7.38" | 5.11" | 4.01" | 3.03" | 2.07" | 2.53" | 3.40" | 6.18" | 10.14" | 14.74" | 12.66" | 99.09" |
| Kapingamarangi | 8.19" | 9.27" | 9.84" | 9.15" | 9.27" | 11.43" | 13.64" | 12.08" | 13.78" | 14.15" | 8.13" | 9.93" | 145.85" |
| Koror | 11.84" | 11.39" | 11.16" | 10.18" | 8.56" | 7.44" | 7.32" | 11.83" | 17.48" | 18.53" | 13.50" | 11.77" | 152.90" |
| Kosrae | 10.94" | 13.83" | 16.11" | 16.67" | 12.93" | 16.06" | 17.51" | 17.75" | 14.64" | 14.91" | 14.22" | 14.22" | 213.87" |
| Kwajalein | 11.18" | 11.28" | 6.66" | 3.16" | 2.64" | 2.35" | 5.26" | 6.72" | 6.93" | 9.87" | 9.74" | 10.74" | 90.41" |
| Lukonor | 11.32" | 9.08" | 11.27" | 8.41" | 8.93" | 9.26" | 11.31" | 11.69" | 11.65" | 15.93" | 14.04" | 10.15" | 151.36" |
| Majuro | 12.73" | 13.44" | 11.39" | 7.74" | 6.88" | 6.58" | 9.42" | 10.11" | 11.01" | 11.17" | 11.69" | 11.17" | 125.25" |
| Pago Pago | 9.26" | 10.14" | 12.84" | 13.34" | 12.00" | 10.68" | 9.39" | 9.66" | 5.33" | 5.55" | 5.38" | 6.53" | 125.57" |
| Pohnpei | 15.27" | 14.83" | 16.08" | 13.18" | 9.55" | 13.17" | 18.41" | 19.96" | 14.81" | 15.43" | 14.26" | 12.55" | 182.36" |
| Saipan | 10.62" | 5.61" | 3.85" | 2.53" | 2.59" | 1.89" | 2.63" | 2.38" | 3.62" | 8.91" | 13.13" | 10.09" | 70.25" |
| Yap | 12.18" | 8.83" | 8.51" | 6.39" | 5.19" | 4.56" | 5.63" | 7.85" | 12.04" | 15.08" | 14.82" | 13.50" | 120.31" |
As measured by percent of normal precipitation, no station was drier than normal in the short term (September and the last 3 months [July-September]) and long term (year to date [January-September] and last 12 months [October 2022-September 2023]). However, Lukunor was drier than normal for 3 of the time periods and wetter than normal for September. Guam, Kwajalein, and Majuro were drier than normal in the short term and near to wetter than normal in the long term. Pago Pago was drier than normal for the last 3 months and near to above normal for the other three time periods. Yap was drier than normal for September but wetter than normal for the other 3 time periods. Airai, Chuuk, Kapingamarangi, Kosrae, Pohnpei, and Saipan were near to wetter than normal for all 4 time periods.
Based on percent of normal average (instead of normal median values), in the Marianas Islands, September was mostly drier than normal across the main islands, August-September was mostly wetter than normal (except on Guam), and the last 3 to 4 months were generally drier than normal. It was predominantly wetter than normal across the main islands at the 6- to 24-month time scales, with some dryness showing up on Saipan at longer time periods (percent of normal precipitation maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months).
Based on percent of normal average (instead of normal median values), in the Marshall Islands, the last 1 to 4 months were drier than normal across most of the islands. The last 6 to 48 months were drier than normal in the southwest and northeast but wetter than normal at the other primary stations. Longer time periods were drier than normal in the southwest (Jaluit) and north (percent of normal precipitation maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months).
According to the September 30 USDM produced for the USAPI, Tutuila (American Samoa) was in moderate drought, while Ailinglaplap, Kwajalein, Majuro, and Wotje (RMI) were abnormally dry, and the rest of the USAPI stations were free of drought and abnormal dryness. Satellite observations of vegetative health (drought stress, stressed vegetation, VHI) indicated there were some areas of stressed vegetation on Guam, but little concern for drought.
September 2023 precipitation ranks ranged from very dry to very wet and everything in between, based on data available at the time of this report. Ailinglaplap, Kwajalein, Majuro, and Wotje had September precipitation that ranked in the top ten driest category, while Kapingamarangi, Mili, and Nukuoro, ranked in the top ten wettest category:
- Ailinglaplap: second driest September (in a 40-year record) and seventh driest July-September.
- Majuro: third driest September (70 years) and July-September, eighth driest May-September.
- Wotje: fourth driest September (40 years), fifth driest August-September, and eighth driest July-September.
- Kwajalein: sixth driest September (72 years) and August-September, but second driest July-September and fifth driest June-September.
- Lukunor: 25th driest September (40 years) but eighth driest July-September, June-September, and April-September, fifth driest December-September and November-September, and sixth driest October-September.
- Pingelap: 20th driest September (40 years) but seventh driest August-September and eighth driest June-September.
- Jaluit: 20th driest September (40 years) but sixth driest April-September and February-September, and seventh driest October-September.
Some stations at the wet end of the scale:
- Kapingamarangi had the wettest September (32 years) and July-September through January-September.
- Pohnpei had the wettest June-September (72 years) and April-September.
- Guam had the wettest December-September (66 years) and April-September.
- Mili had the wettest July-September (38 years) through May-September and January-September through October-September.
The following analysis of historical data for the USAPI stations in the Global Historical Climatology Network-Daily (GHCN-D) dataset, augmented with fill-in data from the 1981-2010 Normals, helps put the current data into historical perspective by computing ranks based on the period of record. The table below lists the precipitation ranks for September 2023, April-September 2023 (last 6 months), and October 2022-September 2023 (the last 12 months). Some stations have a long period of record and their dataset is fairly complete, while other stations have a shorter period of record and the dataset has some missing data.
| Station | September 2023 | Apr-Sep 2023 | Oct 2022-Sep 2023 | Period of Record | |||
|---|---|---|---|---|---|---|---|
| Rank | Years | Rank | Years | Rank | Years | ||
| Ailinglaplap | 2 | 40 | 30 | 39 | 28 | 37 | 1981-2023 |
| Airai | 53 | 73 | 57 | 71 | 69 | 71 | 1951-2023 |
| Chuuk | 35 | 73 | 65 | 72 | 63 | 72 | 1951-2023 |
| Fananu | 6 | 7 | 3 | 3 | -- | 2 | 2003-2023 |
| Guam | 25 | 67 | 66 | 67 | 65 | 66 | 1957-2023 |
| Jaluit | 20 | 40 | 6 | 39 | 7 | 37 | 1981-2023 |
| Kapingamarangi | 32 | 32 | 24 | 24 | 18 | 22 | 1962-2023 |
| Kosrae | 40 | 52 | 30 | 44 | 22 | 35 | 1954-2023 |
| Kwajalein | 6 | 72 | 52 | 71 | 49 | 71 | 1952-2023 |
| Lukunor | 25 | 40 | 8 | 27 | 6 | 26 | 1981-2023 |
| Majuro | 3 | 70 | 24 | 69 | 36 | 69 | 1954-2023 |
| Mili | 36 | 39 | 36 | 38 | 35 | 35 | 1981-2023 |
| Nukuoro | 34 | 41 | 31 | 39 | 34 | 38 | 1981-2023 |
| Pago Pago | 47 | 58 | 33 | 58 | 30 | 57 | 1966-2023 |
| Pingelap | 20 | 40 | 25 | 38 | -- | 34 | 1981-2023 |
| Pohnpei | 63 | 73 | 72 | 72 | 69 | 72 | 1951-2023 |
| Saipan | 29 | 43 | 35 | 43 | 33 | 34 | 1981-2023 |
| Ulithi | 11 | 40 | 36 | 38 | 31 | 34 | 1981-2023 |
| Utirik | -- | 16 | -- | 8 | -- | 3 | 1985-2020 |
| Woleai | 28 | 42 | -- | 33 | -- | 29 | 1968-2023 |
| Wotje | 4 | 40 | 29 | 39 | 25 | 36 | 1981-2023 |
| Yap | 11 | 73 | 66 | 72 | 66 | 72 | 1951-2023 |
SPI values for seven time periods for Pacific Islands, computed by the Honolulu NWS office.
NOAA Regional Climate Centers
More information, provided by the NOAA Regional Climate Centers and others, can be found below.
Southeast
As noted by the Southeast Regional Climate Center, monthly precipitation was below average across much of the Southeast region in September and mean temperatures varied. The driest locations were found across Alabama and northwest Florida, the West Coast of Florida, northern portions of Georgia, South Carolina, and western North Carolina, as well as southeastern North Carolina, where monthly precipitation was less than half and, in some cases, less than a quarter of the expected amount. Muscle Shoals, AL recorded its second driest September on record (since 1893) with just 0.06 inch (1.5 mm) of precipitation. Athens, GA (1898-2023) and Sarasota, FL (1911-2023) recorded their third driest September on record with 0.18 and 1.88 inch (4.6 and 47.8 mm) of precipitation, respectively. Lenoir, NC, located in the western foothills, tied its fourth driest September on record (since 1871) with just 0.65 inch (16.5 mm) of precipitation. Dry weather persisted in the U.S. Virgin Islands. Saint Croix recorded its third driest September on record (since 1951) with 0.76 inch (19.3 mm) of precipitation, while Saint Thomas recorded 2.31 inches (58.7 mm), which is 39 percent of normal. Through the first nine months of the year, Saint Croix has received about 55 percent of its expected precipitation, while Saint Thomas has received about 47 percent.
Monthly temperatures were 1 to 3 degrees F (0.5 to 1.6 degrees C) above average across the West Coast of Florida, southern portions of Alabama and Georgia, western North Carolina, and northern and eastern portions of Virginia. Remarkably, some of the greatest monthly temperature departures in the region were found across the Caribbean, which typically sees small temperature variations due to its tropical latitude. San Juan, PR recorded its warmest month on record (since 1898) with a mean temperature of 85.8 degrees F (29.9 degrees C), breaking the previous record of 85.7 degrees F (29.8 degrees C) set in June 2012. Saint Croix also recorded its warmest month on record (since 1951) with a mean temperature of 87.7 degrees F (30.9 degrees C), breaking the previous record set last month by a full 1-degree F (0.5 degrees C). Lastly, Saint Thomas recorded its third warmest September on record (since 1953).
At the start of the month, about 26 percent of the region was dry or in drought according to the USDM. Moderate (D1) and severe (D2) drought expanded across southern Alabama and the western Panhandle of Florida, with small areas of extreme (D3) drought emerging during the month. Moderate (D1) to extreme (D3) drought expanded slightly across the West Coast of Florida. Moderate (D1) drought emerged across northern portions of Alabama and Georgia, extreme southwest Georgia, and the Eastern Shore of Virginia. Moderate (D1) drought expanded across northern Virginia, while severe (D2) drought persisted across the Shenandoah Valley. Abnormal dryness (D0) expanded across western Alabama, emerged in northeast Florida, and persisted across central portions of Georgia and the Carolinas. Tropical Storm Ophelia helped alleviate some areas of abnormal dryness (D0) and moderate (D1) drought across eastern North Carolina and Virginia. Overall, about 37 percent of the region was dry or in drought by the end of September. In the Caribbean, abnormal dryness (D0) expanded across Puerto Rico and the outlying islands. Severe (D2) drought re-emerged on the northwest side of the island but improved to moderate (D1) drought by the end of the month. Moderate (D1) drought also emerged on the northeast side of the island, including the San Juan area. Drought conditions continued to deteriorate in the U.S. Virgin Islands, with severe (D2) drought emerging on Saint John and exceptional (D4) drought emerging on Saint Thomas and Saint Croix by the end of the month.
Drought conditions have negatively affected many crops in Virginia, including pumpkins and apples, and some yields are expected to be 50 percent lower compared to last year. The continued heat and lack of precipitation resulted in crop damage and some delayed harvests across parts of the Florida Panhandle. Livestock and pastures were in generally good to fair condition across the region. While cooler temperatures helped reduce heat stress, lingering moisture deficits and poor grazing conditions forced operators to use supplemental feed. Planting of fall and winter grasses, as well as winter wheat, was delayed in places due to dry soils. Agricultural conditions continued to deteriorate in the Caribbean.
South
As explained by the Southern Regional Climate Center, hot and dry conditions continue to affect the Southern region, negatively impacting crops/livestock, infrastructure, transportation, and water resources. Above-normal temperatures were prevalent across much of the Southern region, except for Tennessee and isolated portions of eastern Arkansas and northeastern Mississippi where temperatures were typically within 1 degree F of normal for September. Texas experienced its warmest September on record; the Southern region as a whole had its 6th warmest September. Precipitation was below normal for most of the Southern region during September except for central Texas, portions of the Texas and Oklahoma Panhandles, and isolated areas of eastern Texas, Oklahoma, and western Arkansas. The Southern region as a whole had its 29th driest September.
During September, degradation of drought conditions were common in the eastern portion of the Southern region, particularly Mississippi where the central part of the state saw three classes of degradation from August 29th to September 26th. Southern Oklahoma and northern Texas also experienced degradation of drought conditions. Texas experienced some improvement in isolated areas that received much-needed rain during September. The total area experiencing Extreme or Exceptional Drought, according to the USDM, increased from 28 percent to 32 percent during September, with much of this expansion occurring in Mississippi. As of September 26th, at least 65 percent of the Southern region was in some category of drought. The hot and dry conditions have particularly impacted the cotton crops in Oklahoma and Texas, with both states reporting only nine and eleven percent, respectively, of cotton crops being rated as Good to Excellent by the USDA as of October 1st as harvest progresses across the region. Dry and hot conditions have led to burn bans, water restrictions, and low streamflow in many areas affected by drought. Low flows on the Mississippi River have begun to snarl barge traffic and have contributed to saltwater intrusion creeping up the Mississippi towards New Orleans, Louisiana. Rangeland and pasture conditions in the western portions of the region continue to suffer, and there are increasing reports of ranchers reducing the size of their herds due to feed and water limitations.
September saw continued record-breaking heat across Texas, which experienced its warmest September on record and had 14 stations that experienced at least three weeks of 100 F or higher maximum temperatures during September. In drought-affected areas of the region, dry and hot conditions throughout the summer have led to damages to water infrastructure and building foundations due to shrinking of soils.
Midwest
As described by the Midwest Regional Climate Center, the average September temperature for the Midwest was 66 degrees F (18.9 degrees C), which was 2.4 degrees F (1.3 degrees C) above the 1991-2020 normal, and September precipitation totaled 2.38 inches (60 mm) for the region, which was 1.04 inches (26 mm) below normal, or 70 percent of normal. While most of the region had precipitation that was 10-75 percent of normal, precipitation was 75-200 percent of normal from northern Illinois northward into Wisconsin and eastern Minnesota. Preliminary rankings indicate Ohio had its 6th driest September since 1895. Youngstown, Ohio had its 2nd driest September in 96 years. Sault Ste Marie, Michigan had its 3rd driest September in 136 years. Green Bay, Wisconsin had its 4th driest September in 138 years.
Abnormal dryness and drought expanded across the Midwest during September, affecting portions of all nine Midwestern states. The month concluded with about 83 percent of the region dry or in drought, up about 18 percent compared to the start of September. The most severe and widespread drought persisted in the northwest, although normal to above-normal precipitation slightly improved conditions in Minnesota and Wisconsin. Iowa exceeded 170 consecutive weeks of at least moderate drought, the longest drought for the state in the USDM's nearly 24-year period of record. In the east, moderate drought expanded into Indiana, Kentucky, and Ohio as precipitation deficits grew throughout the month.
Northeast
As summarized by the Northeast Regional Climate Center, September started with record warm temperatures and ended with record wet conditions. The Northeast had its 10th warmest September since records began in 1895 with an average temperature of 63.5 degrees F, which was 1.9 degrees F above normal. The Northeast received 4.04 inches of precipitation during September, which was 100 percent of normal. September precipitation for the 12 Northeast states ranged from 71 percent of normal in West Virginia to 215 percent of normal in Connecticut, with eight states being wetter than normal.
The USDM from September 5 showed 2 percent of the Northeast in moderate drought and 5 percent as abnormally dry. Interior parts of the Northeast including western West Virginia, western Pennsylvania, and western New York saw increasing precipitation deficits, below-normal streamflow, and declining soil moisture, leading to the expansion of abnormal dryness. However, heavy precipitation, particularly in late September, chipped away at drought and dryness in the Mid-Atlantic. The USDM from September 26 showed 1 percent of the Northeast in moderate drought and 10 percent as abnormally dry. At times during September, USGS 7-day average streamflow and/or groundwater levels were below normal or lower for western New York, northwestern Pennsylvania, and an area stretching from eastern West Virginia into southern New Jersey, with a couple of gauges reporting record low flows or levels. At least 18 water suppliers in Pennsylvania and several in Maryland and eastern West Virginia asked customers to voluntarily conserve water. Mandatory water restrictions were implemented by a few water suppliers in southern Pennsylvania. Daily drought-monitoring operations were in place through much of September along the Potomac River upstream from Washington, D.C., with low water levels causing boat tours to be canceled along the historic Chesapeake and Ohio (C&O) Canal, which runs along the river, early in the month. In south-central Pennsylvania, some ponds and streams that firefighters use to fight fires in rural areas dried up or ran low and crops such as apples and corn were harvested earlier than usual due to dry conditions.
High Plains
As summarized by the High Plains Regional Climate Center, the High Plains region grappled with warmer temperatures and spotty precipitation this month, which are less-than-ideal conditions for agricultural producers. These conditions delayed harvesting in the region, while others are planting winter wheat on dry soils. After another disappointing winter wheat crop this year, producers yet again started on the wrong foot. With very dry soil conditions, planting has been difficult. Farmers are planting deeper or planting at normal depth with hopes of precipitation. Soybean and corn harvests have begun for many, with initial reports indicating a mixed bag of yields. Irrigated crops have reported slightly below-normal yields, while dryland yields varied widely in Kansas and Nebraska. The timing of planting this year also played a critical role in dryland corn yields, with much higher yields reported for those planted early.
Well-above-normal temperatures continued this month, with many locations in or just outside of their top 10 warmest September. Much of the region experienced 2 to 4 degrees F (1.1 to 2.2 degrees C) above normal and very few locations reported below-normal temperatures. Precipitation was spotty this month, with a sharp divide in distribution in some states. Southwestern Kansas greatly benefited from the moisture, while next to nothing fell north of I-70 in northwestern Kansas. Wyoming continued to be wet, with some places up to 300 percent above their normal precipitation. After a stretch of wet conditions starting in April, northwestern Kansas had the faucet turned off. Goodland had only a trace amount of precipitation, establishing their driest month on record. Nearby Colby received only 0.03 inch (0.76 mm) this month to rank 2nd driest, while just a mere 60 miles to the north and south both received well over 3 inches (7.62 cm) of precipitation.
Drought conditions both improved and worsened across the region, with large changes in the eastern parts of Kansas and Nebraska. Overall, abnormally dry to exceptional drought (D0-D4) was reduced by nearly 1 percent in the High Plains. After slow improvements in central Nebraska, D4 was rapidly expanded once again. Nearly 5 percent of the state is now under D4, and it includes the highest corn-producing county in the state. Conditions did finally improve in central and western North Dakota, after above-normal precipitation. Elsewhere in the region, both localized improvements and degradations were observed.
West
As summarized by the Western Regional Climate Center, this September warm records were broken in Arizona and New Mexico and nearly broken in Montana. Meanwhile, portions of California, Nevada, and Utah experienced average- to below-average temperatures. The Pacific Northwest was characterized by average temperatures and average precipitation for the month. Montana, Nevada, and Northern California saw above-average precipitation totals, while the remainder of California experienced normal to near record dryness. Most of the western United States, however, received average precipitation totals for the month.
According to the USDM at the end of September, drought increased from 31 precent of the West in August to 44 percent. Drought conditions worsened for Arizona and New Mexico with Arizona ranging from abnormally dry to extreme drought and New Mexico from moderate to exceptional drought. Oregon, Washington, and northern Montana continue to experience drought conditions with the average for those states at severe level and some areas are in extreme drought. Nevada and California continue to stay drought free, especially after receiving rain from Hurricane Hilary's remnants last month.
Alaska summary: Temperatures were average across most of Alaska this month with the only anomalous areas being Northern Alaska along the coast of the Beaufort Sea. Barrow recorded temperatures 3.4 degrees Fahrenheit above average at 33.7 degrees and Prudhoe Bay had temperatures 2.6 degrees Fahrenheit above average. Precipitation was above average for Alaska's Panhandle with Port Alexander receiving an extra 24.86 inches, over double the average. They recorded 50.58 inches for the month of September, recording 11.24 inches in one day, which is the 7th largest total daily rainfall in that area's history. Sitka received 7.1 inches above average, and Juneau got 4.49 inches above average. Kotzebue at the border between the Far North and Southwest Alaska also recorded near record rainfall at 1.77 inches above average. The only area with below average precipitation totals was Tanana in Alaska's Interior which recorded 1.52 inches below average.
Hawaii summary: Most of Hawaii recorded average temperatures and precipitation for the month of September, except for Hana on Maui and Honolulu on O'ahu. Hana recorded its driest September ever (4.36 inches below average) receiving 1.83 inches of rain, only 30 percent of the average monthly total. Honolulu received 0.10 inch of rain for the entire month, 0.78 inch below average, and only 11 percent of the average monthly precipitation for September. The dryness has not aided Hawaii's drought conditions with the total increasing to 82 percent of the state under some category of drought. The Big Island ranges from areas of abnormally dry to severe drought with most of the island under moderate drought conditions. The entire west coast of Maui continues to be under severe drought conditions with most of the neighboring islands, Lanai and Moloka'i, also being under moderate to severe drought. O'ahu and Kauai mostly remain in the abnormally dry to moderate drought range at the end of September.