NOAA: Warmest 12 Months on Record for U.S.

By Jillian MacMath, AccuWeather.com Staff Writer
July 13, 2012; 6:22 AM
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The past 12 months in the contiguous U.S. were the warmest since records began in 1895, according to a report released by the National Oceanic and Atmospheric Administration Monday.

July 2011 through June 2012 only narrowly surpassed the record broken last month for the June 2011 through May 2012 period by 0.5 degrees F.

The January 2012 through June 2012 period was the warmest first half of any year on record for the contiguous United States with the national temperature of 52.9 degrees, placing 4.5 degrees F above average.

Though cooler-than-average temperatures were present for the Pacific Northwest and for the beginning half of June in the Southeast, the latter half of June spurred record-breaking temperatures across a large portion of the nation.

Over 170 all-time warm temperature records were broken or tied during the month of June.

AccuWeather Expert Senior Meteorologist Jack Boston believes the dry and mild winter created the warmer-than-normal spring and warmer summer.

"We had a progressive weather pattern during the winter time. The air masses that came across the U.S. came from the west; they were pacific air masses. All the arctic air was cut off. That led to the unusually mild winter," Boston said.

"It was also a very dry winter, so the dryness of the winter helped it stay warm through the spring and into the early summer. The sun was able to more efficiently heat the surface because the surface wasn't wet," he said.

In addition to the heat, drought plagued nation in June.

As of July 3, 56.0 percent of the contiguous U.S. experienced drought conditions, marking the largest percentage of the nation experiencing drought conditions in the 12-year record of the U.S. Drought Monitor, the report reads.

The heat and the drought are related," Boston said.

"Drought conditions and higher-than-normal temperatures feed each other. Sun heats dry surface more efficiently, as all energy goes to heating and not evaporation."

For the full report from NOAA, click here.

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