2012 marked the warmest year on record for the United States and was also the second most extreme weather year yet recorded, the National Oceanic and Atmospheric Administration says.
The hot weather contributed to a record drought which, at its peak, parched 61 per cent of the nation.
Those dry conditions helped spark massive wildfires which charred 3.7 million hectares – the third highest on record, the NOAA said.
The nation suffered through 11 weather disasters that caused $US1 billion ($A956.9 million) in damage, including hurricanes Sandy and Isaac and tornado outbreaks in the Great Plains, Texas and the Ohio Valley.
Every one of the 48 states in the continental United States had an above-average annual temperature in 2012 and 19 of those broke records.
The average temperature for 2012 was 12.9 degrees Celsius, which is 3.2 above the 20th century average, and 1.0 above 1998, the previous warmest year.
The nationally-averaged precipitation total of 67.5 centimetres was 6.5 centimetres below average and the 15th driest year on record.
This was also the driest year for the US since 1988, when 64.1 centimetres of precipitation were observed.
Meanwhile, 2012 was the third year in a row with 19 named tropical storms, 10 of which packed hurricane strength.