Extremely Rare Warmth for the US the Past 12 Months

June 11, 2012; 6:08 PM ET
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Each of the past 12 months from June 2011 to May 2012 ranked nationally in the warmest top third, the first such occurrence for the United States since 1895 and an extremely unusual feat.

The odds of such a feat occurring randomly are 1 in 531,441, according to NOAA's National Climatic Data Center.

Temperatures from June 2011 to May 2012 throughout the contiguous U.S. averaged 56.0 degrees, which is 3.2 degrees above the long-term average.

The past 12 months is now the warmest such stretch for the nation, surpassing the previous record from May 2011-April 2012 by 0.4 of a degree.

It is not hard to image that such a record would be set with each month between June 2011 and May 2012 ranking among the top third warmest--a feat that the nation has never achieved in a 12-month period since record-keeping began in 1895.

March 2012 was the warmest March on record nationally. In the past 12 months, the U.S. also recorded its second warmest May and August and the third warmest April and July and the fourth warmest January.

These months contributed to the U.S. experiencing its second warmest summer, fourth warmest winter and, most recently, warmest spring on record.

The above sentence pertains to meteorological seasons with spring encompassing the months from March to May. During that time this year, the temperature averaged 57.1 degrees throughout the contiguous U.S.

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That is 5.2 degrees above the 1901-2000 long-term average and shatters the previous warmest meteorological spring record from 1910 by 2.0 degrees.

It was not just the nation as a whole that set a record for the warmest spring, but also 31 states--nearly every state from the Plains eastward.

This spring ranked among the top 10 warmest in 11 other states with only Washington and Oregon experiencing near-normal spring temperatures.

The warm records continue when temperatures for the January to May time frame are compared to normal. Temperatures averaged 49.2 degrees during that period, 5.0 degrees above the long-term average.

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