• The combined global land and ocean average surface temperature for the year to date (January – April 2011) was 0.86 F (0.48 C) above the 20th century average of 54.8 F (12.6 C), making it the 14th 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 17th warmest such period on record. The margin of error is +/- 0.36 F (0.20 C). Warmer-than-average conditions were particularly felt across the southern half of Greenland, Siberia, northern Mexico, the southern United States and across Africa. Cooler-than-average regions included central Canada, the northern United States, western Russia, Kazakhstan, Mongolia, extreme southeast Asia and most of Australia.
  • 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). The warmth was most pronounced across parts of the most of the western Pacific Ocean, the tropical Atlantic Ocean, the North Atlantic near Greenland and Canada, and the southern mid-latitude oceans.
  • La Niña conditions continued to weaken in April for the fourth consecutive month, although sea-surface temperatures remained below normal across the central and eastern equatorial Pacific Ocean. According to NOAA’s Climate Prediction Center, La Niña will continue to have global impacts as the event continues to decline, but by late spring neither La Niña nor El Niño conditions are expected to prevail in the region.
  • Effective May 2, 2011, NOAA updated its monthly mean temperature dataset, which is used to calculate global land surface temperature anomalies and trends. The Global Historical Climate Network-Monthly (GHCN-M) version 3 dataset replaced GHCN-M version 2. Beginning with this month’s 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 April was 5.7 percent below average, ranking as the fifth smallest April since satellite records began in 1979.
  • The April 2011 Antarctic sea ice extent was 7.7 percent below average and was fourth lowest April extent since records began in 1979.
  • Northern Hemisphere snow cover extent during April ranked as the 15th smallest on record, while the snow cover extent over North America was the 10th largest and Eurasian snow cover was the fifth smallest April snow cover on record.
  • Average rainfall across Australia was 18 percent above average during April. However, for the first month since June 2010, below-average rainfall was reported in the states of Queensland, South Australia and New South Wales. This broke a streak of nine consecutive months with above-normal rainfall in those states.

Scientists, researchers and leaders in government and industry use NOAA’s monthly analyses 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.

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