The average temperature for the contiguous United States in 2012 was 55.3 degrees F., making it the warmest year in U.S. history.
This dubious distinction is the result of the country's fourth warmest winter, a record warm spring, the second warmest summer, and a warmer than average autumn.
September and December 2012 in particular were warm enough to earn the "hottest on record" title, even though the last four months of the year weren't as unusually warm as the first eight months.
The previous record was 54.3 degrees F. on average, set in 1998. The 20th century average is 52.1 degrees.
Precipitation in 2012 averaged 26.57 inches, about 2.57 inches below average. This means that 2012 is also the 15th driest year for the U.S.