Not Even Close: 2012 Was Hottest Ever in U.S.

2012, the year of a surreal March heat wave, a severe drought in the Corn Belt and a huge storm that caused broad devastation in the Middle Atlantic States, turns out to have been the hottest year ever recorded in the contiguous United States. Last year’s 55.3 degree average replaced the previous record, set in 1998, by a full degree Fahrenheit. Although one degree does not seem like much, it is in fact a huge deal. Also, 34,008 daily high records were set at weather stations across the country, compared with only 6,664 record lows, clearly uneven. Natural variability was one cause of last year’s extreme heat and drought. But of course, the record could not have been broken without global warming. Last year’s weather in the United States began with an unusually warm winter, with relatively little snow across much of the country, followed by a March that was so hot that trees burst into bloom and swimming pools opened early. Then the soil dried out in the March heat, helping to set the stage for a drought that peaked during the warmest July on record. This drought engulfed 61 percent of the nation, killed corn and soybean crops and sent prices spiraling.  Until last year, the coldest year in the historical record for the lower 48 states, 1917, was separated from the warmest year, 1998, by only 4.2 degrees Fahrenheit. That is why the 2012 record, and its one degree increase over 1998, strikes climatologists as so unusual and why it is such a big deal. 2012 also broke the record and became the second-worst on a measure called the Climate Extremes Index. 11 disasters in 2012 have exceeded a threshold of $1 billion in damages, including several tornado outbreaks; Hurricane Isaac, which hit the Gulf Coast in August, and, late in the year, Hurricane Sandy, which caused damage likely to exceed $60 billion in nearly half the states, primarily in the mid-Atlantic region. The derecho, a line of severe, fast-moving thunderstorms that struck central and eastern parts of the country starting on June 29, killing more than 20 people, toppling trees and knocking out power for millions of households also contributed to this record being broken. However for those who did not suffer tremendously from these disasters remember 2012 due to its summer heart wave in which temperatures in some states reached 109 degrees F. 

http://www.nytimes.com/2013/01/09/science/earth/2012-was-hottest-year-ever-in-us.html?ref=earth&_r=0