The globe experienced the 10th warmest May since record keeping began in 1880, as the climate phenomenon La Niña ended its 2011 cycle. The Arctic sea ice extent was the third smallest extent for May on record.

The monthly analysis from NOAA’s National Climatic Data Center is part of the suite of climate services NOAA provides government, business and community leaders so they can make informed decisions.

Global temperature highlights:  May

  • Last month’s combined global land and ocean average surface temperature was the 10th warmest on record for May at 59.50F (15.30 C), which is 0.90 F (0.50 C) above the 20th century average of 58.6 F (14.8 C). The margin of error associated with this temperature is +/- 0.13 F (0.07 C).
  • Separately, the global land surface temperature was 1.31 F (0.73 C) above the 20th century average of 52.0 F (11.1 C), which was the seventh warmest May on record. The margin of error is +/- 0.25 F (0.14 C).
  • The global ocean surface temperature was 0.74 F (0.41 C) above the 20th century average of 61.3 F (16.3 C), making it the 11th warmest May on record. The margin of error is +/- 0.07 F (0.04 C). The warmth was most pronounced in most of the central and western Pacific, most of the Atlantic, and much of the mid-latitude southern ocean regions.

Global temperature highlights: March – May

  • The combined global land and ocean average surface temperature for March – May 2011 was 0.95 F (0.53 C) above the 20th century average of 56.7 F (13.7 C), making it the 10th warmest on record. The margin of error is +/- 0.14 F (0.08 C).
  • The worldwide land surface temperature was 1.62 F (0.90 C) above the 20th century average of 46.4 F (8.1 C)—the 10th warmest such period on record. The margin of error is +/- 0.27 F (0.15 C).
  • The global ocean surface temperature for March – May was 0.70 F (0.39 C) above the 20th century average of 61.0 F (16.1 C) and was the 11th warmest such period on record. The margin of error is +/-0.70 F (0.39 C). The warmth was most pronounced across the central Pacific Ocean, the eastern and equatorial Atlantic, and the mid-latitude southern oceans.

Global temperature highlights: Year-to-date

  • The combined global land and ocean average surface temperature for the year to date (January 2011 – May 2011) was 0.86 F (0.48 C) above the 20th century average of 55.5 F (13.1 C), making it the 12th warmest on record. The margin of error is +/- 0.16 F (0.09 C).
  • The year-to-date worldwide land surface temperature was 1.33 F (0.74 C) above the 20th century average — the 15th warmest such period on record. The margin of error is +/- 0.36 F (0.20 C).
  • The global ocean surface temperature for the year to date was 0.68 F (0.38 C) above the 20th century average and was the 11th warmest such period on record. The margin of error is +/-0.07 F (0.04 C).
  • La Niña conditions dissipated during May 2011. According to NOAA’s Climate Prediction Center, neither La Niña nor El Niño conditions are expected throughout summer 2011.
  • Effective May 2, 2011, NOAA updated its monthly mean temperature dataset, which is used to calculate global land surface temperature anomalies and trend. The Global Historical Climate Network-Monthly (GHCN-M) version 3 dataset replaced GHCN-M version 2. Beginning with the April 2011 Global State of the Climate Report, GHCN-M version 3 is used for National Climatic Data Center climate monitoring products.  More information on this transition can be found at: http://www.ncdc.noaa.gov/ghcnm.

Polar sea ice and precipitation highlights

  • The average Arctic sea ice extent during May was 5.96 percent below average, ranking as the third smallest May since satellite records began in 1979.
  • The May 2011 Antarctic sea ice extent was 1.17 percent above average and was the 14th smallest May extent since records began in 1979.
  • Northern Hemisphere snow cover extent during May was much-below average, ranking as the third smallest on record. The snow cover extent over North America was slightly below average while Eurasian snow cover was much-below average, ranking as the second smallest May snow cover on record.

Scientists, researchers and leaders in government and industry use NOAA’s monthly reports to help track trends and other changes in the world's climate. This climate service has a wide range of practical uses, from helping farmers know what and when to plant, to guiding resource managers with critical decisions about water, energy and other vital assets.