U.S. has its 20th warmest winter, and an unusually quiet start to the year

It was another warm winter for the U.S. during December 2012 - February 2013, ranking as the 20th warmest winter since records began in 1895. For comparison, the previous "non-winter of 2011 - 2012" was the 4th warmest. And after an unusually intense period of extreme weather during 2011 and 2012, during January - February 2013 the U.S. had its quietest two-month period for extreme weather in over three years, according to NOAA's U.S. Climate Extremes Index (CEI). The index tracks the percentage area of the contiguous U.S. experiencing top-10% and bottom-10% extremes in temperature, precipitation, and drought. The CEI during February 2013 was 13%, and was 14% during January. The last time the U.S. had a two-month period with so little extreme weather was March - April 2009. On average, about 20% of the contiguous U.S. experiences top-10% extreme weather as defined by the CEI. In 2012, just two months (October and February) had below-average CEI, so we're off to a great start to 2013. Of course, February wasn't completely without notable weather:

Winter Storm Nemo on February 8 - 9 brought the heaviest snows to Connecticut and central Long Island since the iconic Blizzard of 1888. Aon Benfield estimated damages from the storm at $100+ million.

On February 10, a violent EF-4 tornado carved a path through Hattiesburg and Oak Grove, Mississippi, injuring 82, but miraculously not killing anyone. Aon Benfield estimated damages from the storm at $100+ million.

California had its driest January–February on record.

Georgia had its wettest February on record, leading to dramatic improvements in their multi-year drought.

February 2013 was a quite ordinary one for temperatures, ranking as the 49th warmest February since 1895, said NOAA's National Climatic Data Center (NCDC) in their latest State of the Climate report. No states had a top-ten warmest or coldest February. However, the February temperatures were warm enough to make the 12-month period ending in February 2013 the warmest such 12-month period on record. Forty-two of the 48 contiguous U.S. states had top-ten warmth during the past twelve months, with eight states posting record warmth.


Figure 1. Historical temperature ranking for the U.S. for the winter of 2012 - 2013. Florida, Delaware, and Vermont each had one of their ten warmest winters on record; no states had a top-ten coldest winter. Image credit: National Climatic Data Center (NCDC).


Figure 2. Not driving anywhere today! Snow buries cars in New Haven, CT at the Premier Hotel & Suites on Long Wharf on February 9, 2013, due to Winter Storm Nemo. The storm caused $100+ million in damage. Image credit: wunderphotographer phototex.

Jeff Masters