— -- The Earth's temperature in May was the fourth-warmest May on record, with a reading almost 1 degree warmer than the long-term average, according to the National Climatic Data Center (NCDC) in Asheville, N.C.
Only the Mays in 1998, 2001, and 2005 were warmer. Climate records date back to 1880. The globe's most unusual warmth was measured in the western USA, Alaska, Iceland and much of Europe and Asia, reported the NCDC.
A separate temperature data set, measured from satellites, found that the Earth was about 0.07 degrees above the 20-year average for May. This data set is maintained by scientists at the University of Alabama-Huntsville (UAH).
"Powered largely by an area south of Madagascar where temperatures were as much as 11.7 degrees warmer than seasonal norms, the Antarctic continent had its fifth warmest May in more than 30 years," reported UAH scientists Roy Spencer and John Christy in an e-mail.
For the year to date, the NCDC says the world's temperature was tied with 2003 for the sixth-warmest January-May period on record.
USA in May
In the USA, the May 2009 temperature for the contiguous 48 states was above the long-term average by 1.4 degrees, according to the NCDC.
California, New Mexico, and Utah respectively had their fourth, sixth, and ninth warmest May, while Nevada and Arizona registered their fifth warmest May on record. Only North Dakota, Oklahoma, and Arkansas had an average monthly temperature that was below normal.
El Nino update
El Nino, a periodic warming of the tropical Pacific Ocean that affects weather patterns around the world, could be developing. The Climate Prediction Center's most recent update notes that "current observations and dynamical model forecasts indicate conditions are favorable for a transition from ENSO-neutral conditions to El Nino conditions during June-August 2009."
One of the most intense El Ninos in history was in 1998, which was also the year that the Earth recorded its warmest temperature on record.