U.S. experiences warmest 12-month period on record

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2089

Posted by: Jeff Masters, 6:09 PM GMT on May 08, 2012

The past twelve months were the warmest twelve months in U.S. history, said NOAA's National Climatic Data Center (NCDC) on Tuesday, in their monthly "State of the Climate" report. Temperatures in the contiguous U.S. during May 2011 - April 2012 broke the previous record for warmest 12-month period, set November 1999 - October 2000, by 0.1°F. The past twelve months have featured America's 2nd warmest summer, 4th warmest winter, and warmest March on record. Twenty-two states were record warm for the 12-month period, and an additional nineteen states were top ten warm. NOAA said that the January - April 2012 period was also the warmest January - April period since record keeping began in 1895. The average temperature of 45.4°F during January - April 2012 was 5.4°F above the 20th century average for the period, and smashed the previous record set in 2006 by an unusually large margin-- 1.6°F.

[Dr. Masters gives a chart with info for the ten warmest 12-month periods for the contiguous U.S., and the earliest is 1999]

April 2012 was the third warmest April in the contiguous U.S. since record keeping began in 1895. Ten states had a top-ten warmest April, and no states were cooler than average. But what's really remarkable about April was that eight states--Illinois, Indiana, Kentucky, Michigan, Wisconsin, Ohio, Pennsylvania, and West Virginia--had average April temperatures cooler than their March temperatures, even though their April temperatures were still above the long-term average for the month. These statistics show just how remarkably warm March 2012 was. Most extreme was Illinois, where April 2012 temperatures ranked in the top 20% for warmest Aprils, yet were cooler than March 2012 temperatures.