The year saw a record warm spring, second warmest summer, fourth warmest winter and a warmer-than-average autumn with an average temperature of 55.3 degrees F, a full degree above 1998, the previous warmest year, a NOAA release said Tuesday.
Every state in the contiguous 48 reported an above-average annual temperature for 2012.
Drought and dryness accompanied the warmth, NOAA said, with the average precipitation total for the year for the contiguous states at 26.57 inches, 2.57 inches below average, making 2012 the 15th driest year on record for the nation.
At the peak of drought conditions in July it covered 61 percent of the nation with the Mountain West, Great Plains and Midwest experiencing the most intense conditions.
The U.S. Climate Extremes Index, which evaluates extremes in temperature and precipitation as well as land-falling tropical cyclones, found 2012 had nearly twice the average number of extreme events, second only to 1998.
Eleven disasters in 2012 reached the $1 billion threshold in losses, NOAA said, including Hurricanes Sandy and Isaac and tornado outbreaks in the Great Plains, Texas and Southeast/Ohio Valley.