Global Analysis - May 2011
Note: GHCN-M Data Notice
An omission in processing a correction algorithm led to some small errors on the Global Historical Climatology Network-Monthly dataset (GHCN-M v3.2.0). This led to small errors in the reported land surface temperatures in the October, November, December and Annual U.S. and global climate reports. On February 14, 2013, NCDC fixed this error in its software, included an additional improvement (described below), and implemented both changes as GHCN-M version 3.2.1. With this update to GHCN-M, the Merged Land and Ocean Surface Temperature dataset also is subsequently revised as MLOST version 3.5.3.
The net result of this new version of GHCN-M reveals very small changes in temperature and ranks. The 2012 U.S. temperature is 0.01°F higher than reported in early January, but still remains approximately 1.0°F warmer than the next warmest year, and approximately 3.25°F warmer than the 20th century average. The U.S. annual time series from version 3.2.1 is almost identical to the series from version 3.2.0 and that the 1895-2012 annual temperature trend remains 0.13°F/decade. The trend for certain calendar months changed more than others (discussed below). For the globe, ranks of individual years changed in some instances by a few positions, but global land temperature trends changed no more than 0.01°C/century for any month since 1880.
NCDC uses two correction processes to remove inhomogeneities associated with factors unrelated to climate such as changes in observer practices, instrumentation, and changes in station location and environment that have occurred through time. The first correction for time of observation changes in the United States was inadvertently disabled during late 2012. That algorithm provides for a physically based correction for observing time changes based on station history information. NCDC also routinely runs a .pairwise correction. algorithm that addresses such issues, but in an indirect manner. It successfully corrected for many of the time of observation issues, which minimized the effect of this processing omission.
The version 3.2.1 release also includes the use of updated data to improve quality control and correction processes of other U.S. stations and neighboring stations in Canada and Mexico.
Compared to analyses released in January 2013, the trend for certain calendar months has changed more than others. This effect is related to the seasonal nature of the reintroduced time-of-observation correction. Trends in U.S. winter temperature are higher while trends in summer temperatures are lower. For the globe, ranks of individual years changed in some instances by a few positions, but global temperature trends changed no more than 0.01°C/century for any month since 1880.
More complete information about this issue is available at this supplemental page.
NCDC will not update the static reports from October through December 2012 and the 2012 U.S and Global annual reports, but will use the current dataset (GHCN-M v. 3.2.1 and MLOST v. 3.5.3) for the January 2013 report and other comparisons to previous months and years.
Contents of this Section:
- The combined global land and ocean average surface temperature for May 2011 was 0.50°C (0.90°F) above the 20th century average of 14.8°C (58.6°F). This is the 10th warmest such value since records began in 1880.
- For March–May 2011, the combined global land and ocean surface temperature was 0.53°C (0.95°F) above average—also the 10th warmest March–May on record.
- The combined global land and ocean average surface temperature for January–May 2011 was the 12th warmest on record. The year-to-date period was 0.48°C (0.86°F) warmer than the 20th century average.
- The global land average surface temperature for May 2011 was the seventh warmest May on record, while March–May ranked as the 10th warmest such period.
- In the Northern Hemisphere, both the May 2011 and March–May average temperatures for land areas were seventh warmest such periods on record.
- The May, March–May, and year-to-date (January–May) worldwide ocean surface temperatures all ranked as the 11th warmest such periods on record.
- La Niña ended during May 2011. Sea surface temperature anomalies in the eastern equatorial Pacific Ocean warmed above the La Niña threshold, signifying a return to ENSO-neutral conditions.
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.
Temperature anomalies for May 2011 and March–May 2011 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 1961–90 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.
Temperatures during May 2011 were warmer than average for much of the world's land surface, with the warmest temperature anomalies occurring over northwestern Africa, most of Europe and Russia, southwestern Asia, Alaska, and northwestern Canada. Cooler-than-average regions included the western half of the United States, most of Mexico, much of central and eastern Canada, eastern Russia, and Australia. The worldwide land temperatures for May 2011 ranked as the seventh warmest May on record, 0.73°C (1.31°F) above the 20th century average of 11.1°C (52.0°F). The global temperature dataset period of record dates back to 1880.
The worldwide ocean temperatures during May 2011 were 0.41°C (0.74°F) above the 20th century average, and ranked as the 11th warmest May on record. The warmest sea surface temperatures (SSTs) were present in most of the central and western Pacific Ocean, most of the Atlantic, and much of the southern midlatitude oceans. La Niña, which had been present since July 2010, ended during May as ENSO-neutral conditions returned. According to NOAA's Climate Prediction Center, neither El Niño nor La Niña conditions are expected through summer 2011. The global combined land and ocean surface temperature for May tied with 2000 and 2008 as the 10th warmest on record, at 0.50°C (0.90°F) above the 20th century average of 14.8°C (58.6°F).
The May 2011 average temperature for the Northern Hemisphere (land and ocean surface combined) was 0.58°C (1.04°F) above the 20th century average and was the ninth warmest May on record for the hemisphere. The Northern Hemisphere land surface temperature was seventh warmest, at 0.91°C (1.64°F) above the 20th century average. The ocean surface temperature ranked as the 13th warmest May, at 0.37°C (0.67°F) above the 20th century average.
In southwestern Europe, Spain experienced its third warmest May on record, behind 1964 and 2006, at 2.9°C (5.2°F) above the 1971–2000 average.
The average temperature for the Southern Hemisphere as a whole (land and ocean surface combined) was 0.43°C (0.77°F) above the 20th century average, and tied with 2004 as the 12th warmest May on record. The Southern Hemisphere ocean temperature during May 2011 was the 10th warmest May on record, with an anomaly of 0.46°C (0.83°F) above the 20th century average. The May 2011 Southern Hemisphere land temperatures were 0.24°C (0.43°F) above the 20th century average—the 37th warmest May on record.
Maximum May temperatures across Australia were 1.33°C (2.39°F) below the 1961–90 average, the seventh coolest on record and the coolest since 2000. Maximum temperatures in Queensland were also seventh coolest, while the Northern Territory and South Australia ranked as fifth coolest. Minimum temperature anomalies across Australia were even larger, 1.75°C (3.15°F) below average, the third coolest on record. Queensland and the Northern Territory reported their second lowest May minimum temperatures on record.
In contrast, according to the National Institute of Water and Atmospheric Research (NIWA), New Zealand reported its warmest May since records began in 1909, with the temperature 2.2°C (4.0°F) above the monthly average.
The combined global land and ocean surface temperature during March–May 2011 was 14.23°C (57.65°F) and ranked as the 10th warmest such period on record. The three-month average temperature was 0.53°C (0.95°F) above the 20th century mean of 13.7°C (56.7°F). Warmer-than-average temperatures were present over much of the globe's land surface areas,making the season also the 10th warmest on record, with average temperatures 0.90°C (1.62°F) above the 20th century average. The warmest anomalies occurred across Russia, Western Europe, southwestern Asia, northern Mexico, and the southern United States. Cooler-than-average regions included most of Canada, the northern United States, and Australia. Global ocean temperatures were 0.39°C (0.70°F) above the 20th century average and ranked as the 11th warmest March–May on record. The warmth was most pronounced across the central Pacific Ocean, the eastern and equatorial Atlantic, and the midlatitude southern oceans.
The Northern Hemisphere combined temperature (land and ocean surface) for March–May 2011 tied with 2004 as eighth warmest, at 0.64°C (1.15°F) above the 20th century average. The Northern Hemisphere oceans were the 12th warmest for March–May, with temperatures 0.35°C (0.63°F) above the long-term average. Land surface temperatures in the Northern Hemisphere were the seventh warmest such period on record, with an anomaly of 1.13°C (2.03°F) above the 20th century average.
During the March–May period, the United Kingdom was very warm. According to the Met Office, temperatures across the UK were tied with 2007 as the warmest such period in its 102-year period of record, at 1.8°C (3.2°F) above average.
The Southern Hemisphere combined land and ocean temperature for March–May 2011 was 0.42°C (0.76°F) above the 20th century average, and ranked as the 13th warmest March–May on record. The ocean surface temperature for the hemisphere ranked as 10th warmest, with an average temperature 0.44°C (0.79°F) above the 20th century average. The land surface temperature for the period ranked as 28th warmest, with temperatures 0.32°C (0.58°F) above the 20th century average.
Australia's Bureau of Meteorology reported the coolest March–May (Southern Hemisphere autumn) on record for the country, at 1.40°C (2.52°F) below average. The average autumn maximum temperature was the coolest on record in the Northern Territory while the average minimum temperature was the second coolest. At the same time, it was also the wettest such period on record in the Northern Territory.
The January–May 2011 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 across a large swath of Russia, Alaska, northern and central Mexico, Western Europe, western Africa, and southwestern Asia. Cooler-than-average regions included Eastern Europe, northern China, southeastern Asia, most of Australia, central Canada, and the northern United States. The global land and ocean surface combined temperature for January–May 2011 was the 12th warmest such period on record, with temperatures 0.48°C (0.86°F) above the 20th century average. Global ocean surface temperatures were the 11th warmest January–May on record, with temperatures 0.38°C (0.68°F) above the 20th century average. The average global land surface temperature for the period was 0.74°C (1.33°F) above the 20th century reference period and tied with 1990 as the 15th warmest January–May on record.
The Northern Hemisphere combined temperatures (land and ocean surface) were 0.56°C (1.01°F) above the 20th century average and ranked as the 13th warmest January–May on record. The land surface temperature for the hemisphere tied with 2003 as 14th warmest, with temperatures 0.89°C (1.60°F) above average, while the ocean surface tied with 2001 as the 10th warmest January–May, with temperatures 0.35°C (0.63°F) above the 20th century mean.
The Southern Hemisphere combined temperatures (land and ocean surfaces) tied with 1992 and 1999 as the 13th warmest January–May, with temperatures 0.41°C (0.76°F) above the 20th century average. The average Southern Hemisphere land surface temperature for the year to date tied with 1994 as the 26th warmest January–May on record while the ocean surface temperature tied with 1983 as 11th warmest.
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 2011 map and March–May 2011, 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 2011 from the weekly SST page.
Temperature Rankings and Graphics
(out of 132 years)
|Warmest on Record|
|Land||+0.73 ± 0.14||+1.31 ± 0.25||7th warmest||2010||+1.10||+1.98|
|Ocean||+0.41 ± 0.04||+0.74 ± 0.07||11th warmest||1998||+0.57||+1.03|
|Land and Ocean||+0.50 ± 0.07||+0.90 ± 0.13||10th warmest||2010||+0.70||+1.26|
|Land||+0.91 ± 0.13||+1.64 ± 0.23||7th warmest||2010||+1.20||+2.16|
|Ocean||+0.37 ± 0.04||+0.67 ± 0.07||13th warmest||2005||+0.58||+1.04|
|Land and Ocean||+0.58 ± 0.08||+1.04 ± 0.14||9th warmest||2010||+0.81||+1.46|
|Land||+0.24 ± 0.25||+0.43 ± 0.45||37th warmest||2002||+1.00||+1.80|
|Ocean||+0.46 ± 0.04||+0.83 ± 0.07||10th warmest||1998||+0.62||+1.12|
|Land and Ocean||+0.43 ± 0.06||+0.77 ± 0.11||12th warmest*||1998||+0.67||+1.21|
*Signifies a tie
* Southern Hemisphere Land and Ocean tied with 2004 as 12th warmest on record.
(out of 132 years)
|Warmest on Record|
|Land||+0.90 ± 0.15||+1.62 ± 0.27||10th warmest||2010||+1.28||+2.30|
|Ocean||+0.39 ± 0.04||+0.70 ± 0.07||11th warmest||2010*||+0.56||+1.01|
|Land and Ocean||+0.53 ± 0.08||+0.95 ± 0.14||10th warmest*||2010||+0.76||+1.37|
|Land||+1.13 ± 0.18||+2.03 ± 0.32||7th warmest||2010||+1.40||+2.52|
|Ocean||+0.35 ± 0.05||+0.63 ± 0.09||12th warmest||2010||+0.56||+1.01|
|Land and Ocean||+0.64 ± 0.11||+1.15 ± 0.20||8th warmest*||2010||+0.88||+1.58|
|Land||+0.32 ± 0.18||+0.58 ± 0.32||28th warmest||2010||+0.98||+1.76|
|Ocean||+0.44 ± 0.04||+0.79 ± 0.07||10th warmest||1998||+0.61||+1.10|
|Land and Ocean||+0.42 ± 0.07||+0.76 ± 0.13||13th warmest||1998||+0.66||+1.19|
*Signifies a tie
* Global Ocean warmest years on record are 1998 and 2010.
* Global Land and Ocean tied with 2000 and 2008 as 10th warmest on record.
* Northern Hemisphere Land and Ocean tied with 2004 as 8th warmest on record.
(out of 132 years)
|Warmest on Record|
|Land||+0.74 ± 0.20||+1.33 ± 0.36||15th warmest*||2007||+1.30||+2.34|
|Ocean||+0.38 ± 0.04||+0.68 ± 0.07||11th warmest||2010*||+0.56||+1.01|
|Land and Ocean||+0.48 ± 0.09||+0.86 ± 0.16||12th warmest||2010||+0.71||+1.28|
|Land||+0.89 ± 0.24||+1.60 ± 0.43||14th warmest*||2007||+1.48||+2.66|
|Ocean||+0.35 ± 0.05||+0.63 ± 0.09||10th warmest*||2010||+0.56||+1.01|
|Land and Ocean||+0.56 ± 0.13||+1.01 ± 0.23||13th warmest||2007||+0.85||+1.53|
|Land||+0.34 ± 0.17||+0.61 ± 0.31||26th warmest*||2010||+0.97||+1.75|
|Ocean||+0.42 ± 0.04||+0.76 ± 0.07||11th warmest*||1998||+0.60||+1.08|
|Land and Ocean||+0.41 ± 0.07||+0.74 ± 0.13||13th warmest*||1998||+0.65||+1.17|
*Signifies a tie
* Global Land tied with 1990 as 15th warmest on record.
* Global Ocean warmest years on record are 1998 and 2010.
* Northern Hemisphere Land tied with 2003 as 14th warmest on record.
* Northern Hemisphere Ocean tied with 2001 as 10th warmest on record.
* Southern Hemisphere Land tied with 1994 as 26th warmest on record.
* Southern Hemisphere Ocean tied with 1983 as 11th warmest on record.
* Southern Hemisphere Land and Ocean tied with 1992 and 1999 as 13th warmest on record.
The most current data may be accessed via the Global Surface Temperature Anomalies page.
The maps below represent anomaly values based on the GHCN dataset of land surface stations using a base period of 1961–90. During the May 2011 period, above-average precipitation fell over areas that included the northern half of the United States, Iceland, Scotland, part of southeastern Russia, South Africa, eastern Mongolia, and much of far eastern Asia. The driest anomalies were observed across the southern United States, the southern half of South America, Western Europe, Pakistan, western India, and most of Australia.
According to the UK Met Office, Scotland received 2.5 times its average rainfall during May, making it the country's wettest May since records began in 1909. It was particularly wet in western and northern portions of the country. In contrast, much of southeastern England received just 30 percent of its average monthly rainfall.
Several cities in Argentina recorded their lowest May precipitation totals since 1961, including Iguazú [4.0 mm (0.15 inch)], Rio Fourth [2.0 mm (0.08 inch)], and Trelew [0.5 mm (0.02 inch)].
During March–May 2011, above-average precipitation fell over areas that included much of the United States, Mauritania, northern Sweden, the Philippines, and parts of eastern and northwestern Australia. The areas with the driest anomalies were observed across the southern United States, most of Europe, western India, Pakistan, Mongolia, and most of eastern China.
In Western Europe, England and Wales tied with 1990 as having the driest spring on record since 1910. Regionally, spring 2011 in East Anglia and Kent was the all-time driest three-month period on record.
Additional details on flooding and drought events around the world can also be found on the May 2011 Global Hazards page.
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.