April 2015 Global Climate Report

April 2015 Selected Climate
Anomalies and Events Map

Introduction

Temperature anomalies and percentiles are shown on the gridded maps below. The anomaly map on the left is a product of a merged land surface temperature (Global Historical Climatology Network, GHCN) and sea surface temperature (ERSST.v3b) anomaly analysis developed by Smith et al. (2008). Temperature anomalies 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. The percentile map on the right provides additional information by placing the temperature anomaly observed for a specific place and time period into historical perspective, showing how the most current month, season or year compares with the past.

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

Temperatures

In the atmosphere, 500-millibar height pressure anomalies correlate well with temperatures at the Earth's surface. 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 April 2015 and February–April 2015 maps—is generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.

April

April 2015 Blended Land and Sea Surface
Temperature Anomalies in degrees Celsius

April 2015 Blended Land and Sea Surface
Temperature Percentiles

The average temperature across global land and ocean surface temperatures combined for April 2015 was 0.74°C (1.33°F) higher than the 20^th century average. This was the fourth highest for April in the 136-year period of record, but also marks the lowest monthly departure from average since November 2014.

Examining the data beyond the traditional calendar year, the latest 12-month period (May 2014–April 2015) ties with the record set last month (April 2014–March 2015) as the warmest 12-month period among all months in the 136-year period of record, as shown in the table below. In fact, this record was set several times over the past year, and nine of the ten warmest 12-month periods have occurred within the past two years (September 1997–August 1998 ties as eighth warmest). Nine of these ten 12-month periods also comprise months in two overlapping years. Only the full calendar year of 2014 is among the ten warmest 12-month periods (ties for sixth warmest).

The April 2015 average temperature over land surfaces across the globe was 1.11°C (2.00°F) higher than the 20^th century average, the 10^th highest land temperature on record for the month. Most regions were warmer to much warmer than average, according to the Temperature Percentiles map above. A few areas saw record warmth, including Cuba, part of southern Mexico, small parts of west central South America and southern Brazil, regions of Mauritania, and part of eastern Tanzania. Part of north central Russia had April temperatures more than 5°C (9°F) above average, as shown by the Temperature Departure from Average map above. Cooler-than-average temperatures were notable across large portions of central to western Australia, parts of South Asia, central North Africa, and part of eastern Canada.

Select national information is highlighted below. (Please note that different countries report anomalies with respect to different base periods. The information provided here is based directly upon these data):

• Following its eighth highest March mean temperature, April was notably cooler across Australia with the nationally-averaged mean temperature the 29^th lowest (88^th highest) in the 106-year period of record, at 0.68°C (1.22°F) below the 1961–90 average. Queensland was the only state or territory to see the temperature rise above its statewide average, at +0.03°C (+0.05°F), while all others were below average. Western Australia reported its sixth lowest maximum temperature on record for the month, at 1.78°C (3.20°F) below average, while the maximum temperature for South Australia was 2.11°C (3.80°F) below average.
• Even with a cold snap in the middle of the month, April was about 0.5°–1.2°C (0.9°–2.2°F) above the 1981–2010 average across most of New Zealand.
• The temperature for Norway during April 2015 was 1.8°C (3.2°F) higher than the 1961–1990 average. Finnmark, in the far northeastern portion of the country, saw the highest departures, up to 4°C (7°F) above average.
• For the month, April was warmer than average for Sweden, although not as warm as the recent Aprils in 2011 and 2014. In the northeast of the country, the Torne River in Haparanda was ice free on April 26. This marked the third earliest ice break up for the river on record. The only earlier ice break ups occurred on April 24, 2014 and April 25, 2011, meaning that the three earliest ice break ups of the past 300 years have all occurred in the past five years.
• Spain observed its fourth warmest April since records began in 1961, at 1.7°C (3.1°F) higher than the 1981–2010 average. Only 1997, 2011, and 2014 were warmer during the month.

Similar to the pattern seen over the past several months, it was sea surface temperatures driving the global warmth. The April global sea surface temperature was 0.60°C (1.08°F) higher than the 20^th century average, marking the highest global ocean temperature on record for the month. May 2014–April 2015 ties with April 2014–March 2015 as the warmest 12-month period among all months for the ocean, at 0.59°C (1.06°F) above average. These two latest periods broke the record that had just been set in February (March 2014–February 2015; +0.58°C / +1.04°F), which is now the third warmest 12-month period on record.

During April, record warmth prevailed in part of the Gulf of Alaska and other parts of the northeastern Pacific, part of the equatorial Pacific, and a few areas in each of the other major ocean basins. Record cold sea surface temperatures remained in part of the North Atlantic between Canada and the United Kingdom.

El Niño conditions strengthened in the eastern and central equatorial Pacific in April. Ocean temperature anomalies in the Niño 3.4 region—the area between 5°N and 5°S latitude and 170°W to 120°W longitude where ENSO conditions are monitored—were +1.0°C (+1.8°F) during early May according to NOAA's Climate Prediction Center (CPC), indicating that a weak-to-moderate phase El Niño is present. According to the CPC, there is about a 90 percent chance that El Niño will continue through Northern Hemisphere summer 2015, and more than 80 percent chance it will last through 2015. El Niño conditions tend to enhance global temperatures, with stronger events having generally larger impacts.

April Global Land and Ocean plot

April Global Hemisphere plot

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

Year-to-date (January–April)

January–April 2015 Blended Land and Sea Surface
Temperature Anomalies in degrees Celsius

January–April 2015 Blended Land and Sea Surface
Temperature Percentiles

The first four months of 2015 was the warmest such period on record across the world's land and ocean surfaces, at 0.80°C (1.44°F) above the 20^th century average, surpassing the previous record of 2010 by 0.07°C (0.13°F).

The year-to-date global land surface temperature was 1.48°C (2.66°F) above the 20^th century average. This was the highest for January–April in the 1880-2015 record, surpassing the previous record of 2007 by 0.03°C (0.05°F). The average global ocean surface temperature for January–April was the second highest in the 136-year period of record, at 0.55°C (0.99°F) above average, trailing 1998 by 0.02°C (0.04°F). Record high temperatures in the much of the northeast to central equatorial Pacific, along with large parts of the western equatorial Pacific, contributed to the overall record warmth.

January–April Global Land and Ocean plot

January–April Global Hemisphere plot

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

Precipitation

April

The maps below represent precipitation percent of normal (left, using a base period of 1961–1990) and precipitation percentiles (right, using the period of record) based on the GHCN dataset of land surface stations. As is typical, precipitation anomalies during April 2015 varied significantly around the world.

Select national information is highlighted below. (Please note that different countries report anomalies with respect to different base periods. The information provided here is based directly upon these data):

• According to the Bureau of Meteorology, an East Coast Low in late April brought heavy rainfall to coastal New South Wales, Australia, resulting in extensive damage and several daily and monthly rainfall records. It was the 11^th wettest April on record and wettest April in 25 years for the state.

April 2015 Land-Only Precipitation
Percent of Normal

April 2015 Land-Only Precipitation Percentiles

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.

Citing This Report

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