Warmest periods

Four of the six warmest 12-month periods on record for the U.S. have been set in 2012. (National Climatic Data Center / July 10, 2012)

The nation has marked its warmest 12-month period on record for the third consecutive month in June, though the month was only slightly warmer than normal in Maryland.

The average temperature across the country from July 2011 to June 2012 was 56 degrees, 3.23 degrees above the average temperature across the 20th century, according to a monthly report of the National Climatic Data Center.

That was 0.05 degrees warmer than the average temperature for the 12 months ending in May 2012, the previous record. And it was 0.4 degrees warmer than the 12 months ending in April 2012, the third-warmest period on record.

The warm winter and hot spring and summer that have marked the first half of 2012 were record-setting in themselves. It was the warmest first half of a year on record for the contiguous U.S. at 52.9 degrees, 4.5 degrees above the 20th century average.

The average temperature for June across the country was 71 degrees, 2 degrees above-average.

June's average temperature at BWI Marshall Airport was 73.6 degrees, right around the middle of the rankings all-time at the airport. That average temperature ranks 54th out of 141 years on record for Baltimore.

Precipitation, meanwhile, varied widely across the country in June. Tropical Storm Debby made it the wettest June on record for Florida, while the dry weather that contributed to massive wildfires made it the driest June on record in Wyoming and second-driest in Colorado.

The 2.68 inches of rainfall recorded at BWI ranked 50th among all years dating back to 1871.

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