Every state in the contiguous U.S. had an above-average annual temperature for 2012. Nineteen states had a record warm year and an additional 26 states had one of their 10 warmest.
On the national scale, 2012 started off much warmer than average with the fourth warmest winter (December 2011-February 2012) on record. Winter warmth limited snow with many locations experiencing near-record low snowfall totals. The winter snow cover for the contiguous U.S. was the third smallest on record and snowpack totals across the Central and Southern Rockies were less than half of normal.
Spring started off exceptionally warm with the warmest March on record, followed by the fourth warmest April and second warmest May. The season’s temperature was 5.2°F above average, making it easily the warmest spring on record, surpassing the previous record by 2.0°F. The warm spring resulted in an early start to the 2012 growing season in many places, which increased the loss of water from the soil earlier than what is typical. In combination with the lack of winter snow and residual dryness from 2011, the record warm spring laid the foundation for the widespread drought conditions in large areas of the U.S. during 2012.
The above-average temperatures of spring continued into summer. The national-scale heat peaked in July with an average temperature of 76.9°F, 3.6°F above average, making it the hottest month ever observed for the contiguous United States. The eighth warmest June, record hottest July, and a warmer-than-average August resulted in a summer average temperature of 73.8°F, the second hottest summer on record by only hundredths of a degree. An estimated 99.1 million people experienced 10 or more days of summer temperatures greater than 100°F, nearly one-third of the nation’s population.
Autumn and December temperatures were warmer than average, but not of the same magnitude as the three previous seasons. Autumn warmth in the western U.S. offset cooler temperatures in the eastern half of the country. Although the last four months of 2012 did not bring the same unusual warmth as the first 8 months of the year, the September through December temperatures were warm enough for 2012 to remain the record warmest year by a wide margin.
The nationally-averaged precipitation total of 26.57 inches was 2.57 inches below average and the 15th driest year on record for the lower 48. This was also the driest year for the nation since 1988 when 25.25 inches of precipitation was observed.
The driest conditions during 2012 occurred across the central United States. Two states, Nebraska and Wyoming, had their driest years on record. Eight additional states had annual precipitation totals ranking among the bottom ten. Drier-than-average conditions stretched from the Intermountain West, through the Great Plains and Midwest, and into the Southeast. Wetter-than-average conditions occurred in the Pacific Northwest, where Washington had its fifth wettest year on record, as well as parts of the Gulf Coast and Northeast.
Each season of 2012 had precipitation totals below the 20th century average: