2013: A Warm and Wet Year in the U.S.

After experiencing its hottest and second most extreme year on record in 2012, the contiguous U.S. weather in 2013 was much closer to average, according to the just-released annual climate summary from NOAA's National Climatic Data Center (NCDC). The annual U.S. average temperature was 0.3°F above the 20th century average, ranking as the 37th warmest year in the 119-year record. It was the coolest year since 2009. No states had a top-ten warmest or coolest year on record, though some cities in California and Florida had their warmest year on record, and some cities in the Plains and Mid-South had their coolest year on record. Overall, it was a wet year in the contiguous U.S., ranking as the 21st wettest year in the 119-year record, and wettest since 2009. Michigan and North Dakota had their wettest year on record, and eight other states had top-ten wettest years on record. However, California had its driest year on record, and Oregon had a top-ten driest year on record.


Figure 1. Historical temperature ranking for U.S. states in 2013. No states had a top-ten warmest or coolest year on record. Image credit: National Climatic Data Center (NCDC).


Figure 2. Historical precipitation ranking for U.S. states in 2013. Ten states had a top-ten wettest year on record, and two states had a top-ten driest year. Image credit: National Climatic Data Center (NCDC).

A near-normal year for extremes
The year 2013 in the contiguous U.S. was near normal for extremes, according to NOAA's U.S. Climate Extremes Index (CEI), which tracks the percentage area of the contiguous U.S. experiencing top-10% and bottom-10% extremes in temperature, precipitation, and drought, plus winds from landfalling tropical storms and hurricanes. The CEI was 18% in 2013, close to the long-term average of 20%. The primary contributor to extremes in the CEI was drought, which affected about double the area it usually does in 2013. In 2012, the CEI hit 39%, the second highest value going back to 1910.


Figure 3. NOAA's U.S. Climate Extremes Index (CEI) put 2013 near-average for extreme weather, with 18% of the contiguous U.S. experiencing top-10% extremes. The average is 20% (heavy black line.)

A below-average year for tornadoes
Like 2012, tornado activity across the U.S. during 2013 was below average. There were 742 confirmed tornadoes from January - September, with 149 preliminary tornado reports still pending for October - December, according to NOAA's Storm Prediction Center. This gives 2013 a preliminary tornado count of 891. Depending on the final confirmation rate, this could be the slowest tornado year since 1989, when 856 tornadoes were confirmed. The 1991-2010 annual tornado average is 1,253. Despite the below-average number of annual tornadoes, there were several destructive tornado outbreaks that led to significant damage and loss of life. There were 54 tornado deaths in 2013, and five severe weather and tornado outbreaks that resulted in at least $1 billion in damage each.


Figure 4. Flipped vehicles are piled up outside the heavily damaged Moore Medical Center in Moore, Oklahoma, after an EF-5 tornado ripped through the area on May 20, 2013. A Midwest tornado outbreak on May 18 - May 22 killed 29 people and cost $3.75 billion, making it the most costly weather-related disaster in the U.S. during 2013. Image credit: Brett Deering/Getty Images)

Jeff Masters