While last year was the hottest on record worldwide, the contiguous United States experienced extremes on both ends of the thermometer.
Arizona, California and Nevada notched their highest annual temperatures since record keeping began in 1895, the National Oceanic and Atmospheric Administration reported on January 12. (A 1 on the map represents a state’s coldest year in 120 years; 120 represents its hottest.) Four days later, NASA and NOAA revealed that 2014 was Earth’s warmest year since 1880 (see map below). Yet nine states extending south from the Great Lakes to the Gulf of Mexico experienced the opposite, reporting a year among the top 12 coldest.
The country’s thermal divide stemmed primarily from the polar jet stream, a strong high-altitude air current usually situated over the Arctic. During early 2014, the jet stream frequently dipped far southward over the nation’s midsection, delivering brutal cold to the Midwest while leaving the western United States (including Alaska, which had its hottest recorded year) uncommonly warm and dry.
California surpassed its previous annual record high by a full degree Celsius, which exacerbated the state’s ongoing drought (SN: 1/10/15, p. 16). Seven additional western states sweated through one of their five warmest years on record, according to the Jan. 12 report.
Overall, the continental United States had an average temperature of 11.44° C (52.59° Fahrenheit) in 2014, which ties 1977 for the 34th warmest ever recorded. Despite the early-year cold spell, 2014 marked the 18th consecutive year that the temperature exceeded the 20th century annual average of 11.17° C.
Editor’s note: The main map on this story was updated on February 24, 2015, to correct the colors of Delaware, Florida and Rhode Island. The three states’ 120-year rankings remain unchanged; only their colors have been altered.