Contents of this Section:

• Introduction
• Temperatures
• Precipitation
• References

---

Global Highlights

• The combined global land and ocean average surface temperature for May 2010 was 0.69°C (1.24°F) above the 20^th century average of 14.8°C (58.6°F). This is the warmest such value on record since 1880.
• For March–May 2010, the combined global land and ocean surface temperature was 14.4°C (58.0°F) — the warmest March-May on record. This value is 0.73°C (1.31°F) above the 20^th century average.
• The combined global land and ocean average surface temperature for January–May 2010 was the warmest on record. The year-to-date period was 0.68°C (1.22°F) warmer than the 20^th century average.
• The worldwide ocean surface temperature for May 2010 was the second warmest May on record, behind 1998, 0.55°C (0.99°F) above the 20^th century average of 16.3°C (61.3°F).
• The seasonal (March–May 2010) worldwide ocean surface temperature was the second warmest such period on record, 0.55°C (0.99°F) above the 20^th century average of 16.1°C (61.0°F).
• The global land surface temperatures for May and the March–May period were the warmest on record, at 1.04°C (1.87°F) and 1.22°C (2.20°F) above the 20^th century average, respectively.
• In the Northern Hemisphere, both the May 2010 average temperature for land areas, and the hemisphere as a whole (land and ocean surface combined), represented the warmest May on record. The Northern Hemisphere ocean temperature was the second warmest May on record. The average combined land and ocean surface temperature for the Northern Hemisphere was also record warmest for the March–May period.
• El Niño ended during May 2010. Sea surface temperature anomalies in the eastern equatorial Pacific Ocean cooled below the El Niño threshold, signifying a return to ENSO-neutral conditions. According to NOAA's Climate Prediction Center, sea surface cooling could result in a La Niña during the Northern Hemisphere summer 2010.

---

Please Note: The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. Effective with the July 2009 State of the Climate Report, NCDC transitioned to the new version (version 3b) of the extended reconstructed sea surface temperature (ERSST) dataset. ERSST.v3b is an improved extended SST reconstruction over version 2. For more information about the differences between ERSST.v3b and ERSST.v2 and to access the most current data, please visit NCDC's Global Surface Temperature Anomalies page.

---

Introduction

Temperature anomalies for May 2010 and March 2010 - May 2010 are shown on the dot maps below. The dot maps on the left provide a spatial representation of anomalies calculated from the Global Historical Climatology Network (GHCN) dataset of land surface stations using a 1961-1990 base period. The dot maps on the right are a product of a merged land surface and sea surface temperature (SST) anomaly analysis developed by Smith et al. (2008). For the merged land surface and SST analysis, temperature anomalies with respect to the 1971-2000 average for land and ocean are analyzed separately and then merged to form the global analysis. For more information, please visit NCDC's Global Surface Temperature Anomalies page.

May

Temperatures during May 2010 were warmer than average for much of the world’s land surface, with the warmest temperature anomalies occurring over eastern North America, eastern Brazil, Scandinavia, eastern Europe, equatorial and southern Africa, eastern Russia, and southern Asia. In eastern North America temperatures were 2°C (3.6°F) to 4°C (7.2°F) above normal. According to Environment Canada, some locations in Ontario had their warmest May on record. The warmth over southern Asia was also notable, with the Chinese Province of Yunan having its warmest May since 1951. Anomalously cool temperatures were present for western North America, northern Argentina, western Europe, and interior Asia. According to the German Meteorological Service (Deutscher Wetterdienst), Germany experienced its coolest May since 1991 and its 12^th coolest May on record. The worldwide land temperatures for May 2010 ranked was the warmest May on record, 1.04°C (1.87°F) above the 20^th century average of 11.1°C (52°F). The global temperature dataset period of record dates back to 1880, with 131 years of May data.

The worldwide ocean temperatures during May 2010 were 0.55°C (0.99°F) above the 20^th century average, and ranked as the second warmest May on record, behind 1998. The warmest sea surface temperatures (SSTs) were present in the tropical Atlantic, southern Pacific, and Indian Ocean. The warm SSTs which have been present for the year-to-date over the equatorial East Pacific decreased, signifying the end of El Niño and the return to ENSO-neutral conditions. According to NOAA's Climate Prediction Center, the sea surface cooling could result in a La Niña during the Northern Hemisphere summer 2010. Below-average SSTs during May occurred across the southern oceans, the southeast and northeast Pacific, and the central North Atlantic. The global combined land and ocean surface temperature average for May was the warmest on record. The globally averaged temperature for both land and ocean surfaces was 0.69°C (1.24°F) above the 20^th century average of 14.8°C (58.6°F).

The May 2010 average temperature for the Northern Hemisphere (land and ocean surface combined) was 0.77°C (1.39°F) above the 20^th century average and was the warmest May on record for the hemisphere. The Northern Hemisphere land surface temperature was also record warm, at 1.14°C (2.05°F) above the 20^th century average. Meanwhile, the ocean surface temperature ranked as second warmest May, behind 2005, with a temperature of 0.54°C (0.97) above the 20^th century average.

The India Meteorological Department (IMD) reported that Delhi, India was anomalously warm during the month. The average daily maximum temperature for May was 41.5°C (106.7°F), which is 1.9°C (3.4°F) above the long-term average. The highest temperature experienced during the month was 45.4°C (113.7°F); the all-time maximum May temperature for Dehli is 47.2°C (116.9°F) which occurred on May 29^th 1944. Minimum daytime temperatures during the month were also very warm, averaging 27.8°C (82.0°F), which is 1.9°C (3.4°F) above the long-term mean.

According to the Pakistani Meteorological Service, a record-breaking heatwave affected portions of that country during the last week of May. Temperatures on May 26^th soared to over 53.0°C (127.4°F) in several locations, which the highest temperature of 53.5°C (128.3°F) measured in MahenjuDaro.

The average temperature for the Southern Hemisphere as a whole (land and ocean surface combined) was 0.61°C (1.10°F) above the 20^th century average, and tied for second warmest May on record with 2002 and behind 1998. The Southern Hemisphere ocean temperatures during May 2010 were the second warmest May on record, behind 1998, with an anomaly of 0.58°C (1.04°F) above the 20^th century average. The May 2010 Southern Hemisphere land temperatures were 0.78°C (1.40°F) above the 20^th century average — the fourth warmest May on record.

According to Australia’s Bureau of Meteorology (BoM), May 2010 had above-normal temperatures for most of the country. The monthly national average of daily maximum temperatures were 0.23°C (0.4°F) above normal, with the warmest anomalies occurring in Western Australia, the far northern tropics, northwestern Victoria, and parts of South Australia. The coolest maximum temperatures occurred in the central Northern Territory and northeastern West Australia. During the month, daily minimum temperatures averaged 0.2°C (0.4°F) above normal with warm temperature anomalies as high as 4°C (7.2°F) occurring in the Northern Territory. Cool anomalies of up to 2°C (3.6°F) occurred along the east and west coasts of Australia.

New Zealand experienced above normal temperatures during May 2010. According to New Zealand's National Institute of Water and Atmospheric Research (NIWA), the nationally averaged temperature for the month was 0.6°C (1.1°F) above the 1971–2000 reference period. Some locations had monthly warm anomalies up to 1.2°C (2.2°F) above average, while other locations had below-averge to near-normal temperatures for the month.

Season (March–May)

The combined global land and ocean surface temperature during March–May 2010 was 14.4°C (58.0°F) and ranked as the warmest such period on record. The three-month average temperature was 0.73°C (1.31°F) above the 20^th century mean of 13.7°C (56.7°F). Warmer-than-average temperatures were present over most of the globe’s land surface areas. The global land surfaces were also record warm for the period, with average temperatures 1.22°C (2.20°F) above the 20^th century average. The warmest anomalies occurred over eastern and northern North America, eastern Brazil, northern Africa, eastern Europe, and southern Asia. Meanwhile, anomalously cool conditions were present over eastern Asia and the western United States. Global ocean temperatures were 0.55°C (0.99°F) above the 20^th century average and ranked as second warmest March–May, behind 1998. Very warm SSTs occurred across the tropical Atlantic Ocean, with above average temperatures present in the Indian Ocean, and the southern and northwest Pacific Ocean. Cooler-than-normal ocean temperatures were present in the non-equatorial eastern Pacific, the central North Atlantic, and the Southern Oceans.

The Northern Hemisphere combined temperature (land and ocean surface) for March–May 2010 was record warm, with temperatures 0.86°C (1.55°F) above the 20^th century average. The Northern Hemisphere oceans were also record warm for March–May with temperatures 0.55°C (0.99°F) above the long-term mean. The extraordinary warmth in the North Atlantic contributed to the seasonal record. Land surface temperatures in the Northern Hemisphere were the warmest March–May on record, with an anomaly of 1.35°C (2.4.°F) above the 20^th century average.

During the March–May period, the northeastern U.S. and eastern Canada were very warm. According to the dot map analysis above, temperature anomalies were as high as 5°C (9°F) above average for the region. For the spring period, the northeastern U.S. experienced its warmest such period in the 116 year record.

According to the United Kingdom Meteorological Office, temperatures across the United Kingdom (U.K.) were near normal for the March–May period with the average temperature of 7.6°C (45.7°F) only 0.2°C (0.4°F) above the 1971-2000 average. Spring temperature conditions across the Irish Republic were similar to those of the U.K., with average temperatures slightly above normal. However, according to the Irish Meteorological Service, their spring was the coolest March–May period since 2001 after a string of warm springs.

The Southern Hemisphere combined land and ocean temperature for March–May 2010 was 0.62°C (1.12°F) above the 20^th century average, and ranked as second warmest March–May, behind 1998. The ocean surface temperature for the hemisphere also ranked as second warmest, behind 1998, with an average temperature 0.57°C (1.03°F) above the 20^th century average. The land surface temperature for the period ranked as third warmest, with temperatures 0.88°C (1.58°F) above the 20^th century average.

According to New Zealand’s NIWA office, the average autumn temperature for the nation was 13.8°C (56.8°F), which is 0.5 (0.9°F) above the March–May average. The South Island and the coastal regions of the North Island experienced warm temperature anomalies as high as 1.2°C (2.2°F). Temperatures were generally near average for the rest of New Zealand.

The Australian BoM reported that the autumn (March–May) temperatures for the country were genereally warm with the average daily maximum temperatures for the period being 0.36°C (0.6°F) above normal. The Northern Territory and Queensland had below-average autumn temperatures, but above-average temperatures occurred everywhere else. Tasmania and Western Australia were particularly warm, with March–May temperatures in Tasmania tying with 1998 as record warmest. The average daily minimum March–May temperatures were 0.72°C (1.3°F) above average for Australia, and ranked as the 11^th warmest March–May on record. Some locations in the Northern Territory had average daily minimum temperatures of 3°C (5.4°F) above normal during Autumn.

Year-to-date (January-May)

The January-May 2010 map of temperature anomalies shows above-average temperatures over most of the globe’s surface area. The warmest surface temperature anomalies for the year-to-date period occurred over Canada, the northern U.S., southern Greenland, northern Africa, southwest Asia, Siberia, southern Australia, the tropical North Atlantic, and the equatorial Pacific Ocean. Cool temperature anomalies were present for the southeastern U.S., central Asia, western Europe, non-equatorial eastern Pacific Ocean, and the southern oceans. The global land and ocean surface combined temperature for January–May 2010 was the warmest such period on record with temperatures 0.68°C (1.22°F) above the 20^th century average. Global ocean surface temperatures were second warmest January–May on record, behind 1998, with temperatures 0.54°C (0.97°F) above the 20^th century average. The average global land surface temperature for the period was 1.05°C (1.89°F) above the 20^th century reference period and ranked third warmest January–May on record.

The Northern Hemisphere combined temperatures (land and ocean surface) were 0.75°C (1.35°F) above the 20^th century average and ranked as third warmest January–May. The land surface temperature for the hemisphere ranked as fourth warmest with temperatures 1.11°C (2.0°F) above average, and the ocean surface ranked as warmest January–May with temperatures 0.53°C (0.95°F) above the 20^th century mean. The Southern Hemisphere combined temperatures (land and ocean surfaces), and ocean surface temperatures, ranked as second warmest with temperatures 0.61°C (1.10°F) and 0.57°C (1.03°F) above the 20^th century average, respectively. The average Southern Hemisphere land surface temperature for January-May 2010 was the warmest January–May on record with temperature anomalies of 0.89°C (1.60°F) above the 20^th century average.

[ top ]

---

The average position of the upper-level ridges of high pressure and troughs of low pressure (depicted by positive and negative 500-millibar height anomalies on the May 2010 map and March 2010 - May 2010, respectively) are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively. For other Global products, please see the Climate Monitoring Global Products page.

Images of sea surface temperature conditions are available for all weeks during 2010 from the weekly SST page.

---

Temperature Rankings and Graphics

Current Month | Seasonal | Year-to-date

The most current data may be accessed via the Global Surface Temperature Anomalies page.

[ top ]

---

Precipitation

The maps below represent anomaly values based on the GHCN dataset of land surface stations using a base period of 1961-1990. During the March–May 2010 period, above-average precipitation fell over areas that included Bangladesh, eastern Asia, central South America, eastern Europe, and the U.S. Florida peninsula. The driest anomalies during March–May 2010 were observed across southeast Asia, the Hawaiian islands, eastern Brazil, southern Chile, the southern Pacific Islands, eastern Australia, and South Africa.

During May 2010, above-average precipitation fell over areas that included eastern and central Europe, southeast China, the southern Caribbean, northern Argentina, parts of the U.S., and New Zealand. The areas with the driest anomalies during May 2010 were observed across the southern U.S., eastern Brazil, southern Chile, Thailand, and the western equatorial Pacific Islands.

According to the Beijing Climate Center, May 2010 average precipitation over China was 107.8 mm (4.2 inches), which was 15.2 mm (0.6 inches) higher than the 1971-2000 average. The northern provinces of Inner Mongolia and Jilin experienced their wettest May on record, which extends back to 1951. Liaoning province had its second wettest May since 1951.

According to New Zealand's NIWA office, New Zealand had a dry March–May period, with rainfall values typically 50 to 80 percent below the Southern Hemisphere autumn (March–May) normal. However, the southern portions of the South Island was exceptionally wet with precipitation more than 150 percent of normal. Conversely, May brought wet conditions to most of the eastern portions of the country. Most of the autumn rainfall for New Zealand fell during May. Rainfall totals of more than double the May average were widespread for the eastern coasts of both the North and South Islands. Conversely, the west coasts of both islands were dry, with less than half of the typical rainfall amounts.

The Irish Republic was dry on both the monthly (May) and seasonal (March–May) time scale, according to the Irish Meteorological Service. Most of the precipitation to affect Ireland during spring fell during March and April and was in the form of snow and ice. Seasonal precipitation values were around three quarters of the seasonal average at nearly all locations. During May, it rained between 8 and 10 days during the month, with most stations receiving less than the half of their normal May precipitation amounts. On average, Ireland receives rainfall on 12 to 16 days during May.

According to the Indian Meteorological Department, the Indian state of Delhi received a total of 5.4 mm (0.2 inches) during May, compared to the May average of 17.9 mm (0.7 inches). The weather pattern during the month was dominated by high pressure, with only a few westerly disturbances bringing precipitation.

The U.K. meteorological office reported below-average rainfall for the Northern Hemisphere spring (March–May). It was the driest spring since 1984 and 12^th driest in the U.K. since 1910. April and May were particularly dry months, with less than 50 percent of the monthly average rainfall recorded over much of England and Wales. May brought below-average rainfall across almost all of the U.K. with precipitation totals less than 50 percent of normal. Parts of western Scotland, central southern England and a broad swath from East Anglia to Cumbria were exceptionally dry. It was the driest May across the U.K. since 1998.

According to the Australian BoM, the May national rainfall was six percent above the long-term average. It was a wet month over most tropical areas of Western Australia and the Northern Territory. In these regions, for which May is normally the first month of the dry season, rainfall was well above normal. Most other areas were drier than average, particularly in Queensland, where statewide rainfall was 48 percent below normal. Large parts of inland New South Wales, Victoria, Tasmania and western West Australia were also drier than normal. The autumn season (March–May) as a whole was wet for Australia, with the nationally averaged precipitation 11 percent above the long-term mean, with above-normal precipitation amounts covering large parts of the eastern two-thirds of the country, especially in the southern tropics and subtropics. New South Wales and Victoria both had their wettest autumns in at least 10 years.

Additional details on flooding and drought events around the world can also be found on the May 2010 Global Hazards page.

[ top ]

---

References

Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.

Quayle, R.G., T.C. Peterson, A.N. Basist, and C. S. Godfrey, 1999: An operational near-real-time global temperature index. Geophys. Res. Lett., 26, 333-335.

Smith, T.M., and R.W. Reynolds (2005), A global merged land air and sea surface temperature reconstruction based on historical observations (1880-1997), J. Clim., 18, 2021-2036.

Smith, et al (2008), Improvements to NOAA's Historical Merged Land-Ocean Surface Temperature Analysis (1880-2006), J. Climate., 21, 2283-2293.

[ top ]