Key DC Snow Trends

 

Photo Credit: Lee Laudicina

Since the Nation’s Capital got its first significant snowfall in nearly two years with 2.3” on January 31, there have been several more days with relatively light accumulating snows.  Washingtonians had a total of 3.8” of snow so far this winter and that’s all occurred since late January.  My colleagues and I on the WUSA9 Weather Team are watching as a more significant winter storm gets underway tomorrow night and continues into the first part of Friday.  That underscores the need to discuss some key winter weather trends in the DC Metro Area.

Fourteen of the last 20 winters have had below average snowfall in the Nation’s Capital.  However, despite that trend four of DC’s 10 largest winter storms have occurred just since 2003.  In fact, DC’s snowiest winter on record was in 2009-2010 and featured two of its largest winter storms.  February 2010 finished as DC’s second snowiest February and second snowiest month overall, with 32.1”.  More than half of that total occurred with “Snowmageddon” (17.8”). 

February 2010 remains one of only four months on record with at least 30” of snow in the Nation’s Capital.  It was the first month to do so since February 1979, when DC had its third largest winter storm over Presidents’ Day weekend (18.7”).  Seven of DC’s 10 snowiest months owe their place on that memorable list in large part to having had one of DC’s 10 largest snowstorms.  For example, January 1928 ranks as DC’s third snowiest month with 31.5” and 28” of that occurred during the largest snowstorm on record in the Nation’s Capital known as the “Knickerbocker Storm.”

While meteorological winter runs from December 1 through February 28, DC averages accumulating snowfall in the five consecutive months starting in November.  There have been several examples in recent years of heavier snowfall occurring either in late fall or in the changeable month of March.  March has been DC’s snowiest month of the year on five occasions since the 2008-2009 winter.  Also, the 1.4” of snow that occurred in November 2018 made it DC’s snowiest November since 1989. 

These trends were factored into NOAA’s updated data set for what constitutes “average” weather conditions.  NOAA recently updated its running 30-year period to 1991-2020, replacing 1981-2010.  As a result, the Nation’s Capital averages less snowfall than it did previously.  That’s largely due to the fact that the 1980s were a snowier decade than the 2010s were in the DC Metro Area.  Several factors have contributed to that including a more pronounced urban heat island effect as suburban Washington, D.C. has become much more urbanized and, thereby, warmer than previous years.  Snow lovers shouldn’t fret, however, as the right ingredients need to come together only once to create a major winter storm.

DC’s Snowiest Months with any of the Top 10 Snowfalls that Occurred in Those Months

1.  35.2” (February 1899): 20” (February 12-14)
2.  32.1” (February 2010): 17.8” (February 5-6)
3.  31.5” (January 1928): 28” (January 27-29)
4.  30.6” (February 1979): 18.7” (February 18-19)
5.  28.7” (February 2003): 16.4” (February 16-18)
6.  24.4” (January 1935)
7.  23.8” (January 1996): 17.3” (January 7-9)
8.  22.6” (January 1918)
9.  21.0” (February 1983): 16.6” (February 10-11)
10.  20.8” (January 1987)

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DC’s Snowiest Winters (Source: NOAA)

1.  56.1” (2009-2010)
2.  54.4” (1898-1899)
3.  46.0” (1995-1996)
4.  42.5” (1921-1922)
5.  41.7” (1891-1892)
6.  41.0” (1904-1905)
7.  40.4” (2002-2003, 1957-1958)
9.  40.3” (1960-1961)
10.  39.8” (1910-1911)