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Posted at 01:15 PM ET, 02/19/2013

When is the average last date of measurable snow in Washington, D.C.?


As snow lovers have now heard countless times, it’s been more than two years since D.C. last saw meaningful snow accumulations of at least 2 inches. The start of February added a couple of dustings to this winter’s paltry snow total, but we’re still at 1.5” for the season.

With snow opportunities starting to dwindle, some of you might wonder: When does D.C. typically record its last measurable snow of the season?

For Reagan National Airport, the 1981-2010 average last date of measurable snow (defined as at least 0.1”) is February 24 – right around the corner. While we could debate that National Airport isn’t the best snow guide to follow, it generally gives an idea of when snow chances begin to diminish for the region as a whole.


If we look at the last 32 years at Reagan National (DCA), exactly half saw the last measurable snow occur by the end of February. Looking at the glass half full, though, snow in the first half of March is also pretty common.

During the Snowmageddon winter of 2010, a final 0.1” topped off D.C.’s record-snowiest winter on February 27 – which was followed by D.C.’s first March without a freeze. Yet, a year later, the La Niña winter of 2010-11 picked up 0.2” on March 27. This was the fifth-latest date of accumulating snow at DCA since observations began there in 1945.


Since 1980, the latest date that saw accumulating snow in D.C. was April 7, 2007, when 0.4” fell. The earliest date of last measurable snow in this time period (and also on record) was December 9, during the El Niño winter of 1997-98. The 0.1” of snow recorded that year ended up being the only accumulating snow D.C. saw the entire winter!

If we ignore this early December outlier from 1997, it pushes D.C.’s average final average date of accumulating snow a few days later – to February 27. Still, it’s a reminder that snow inside the Beltway is harder to come by as we enter meteorological spring. If we compare the 30-year climate normals with the longer term, the current snow “cutoff” date is about 3 days earlier than the 1946-2012 average, i.e. all years at National Airport.

Does a winter with little snow all season mean snow accumulation also ends earlier? It depends. In recent years, the data show that early snow cutoff dates often coincide with winters of below average snowfall. The seasonal snowfall in 2002, for example, was 3.2 inches – and the last date of accumulating snow was February 7.

On the other hand, some years feature little snowfall with most of it occurring relatively late from one big storm. This happened during the winter of 2008-2009, when D.C. recorded only 7.5” for the season, but 5.5” fell on March 1-2.



If we look at Washington’s entire snow record (from 1888), we see that the latest snowfall dates all occurred in April. While weather observations were at 24th and M Street prior to 1945, it’s still impressive that D.C. recorded up to 2 inches of snow as late as April 12 almost a century ago.

Other notable late-season snowfalls include 5.0” on April 1, 1924 as well as the late March snowstorm that buried D.C. under 11.5 inches of white on March 29, 1942.

Related: Is April snow in D.C. becoming more rare?

Winter enthusiasts can only hope that our lengthy snow drought ends with a surprise late-season storm. And who knows – maybe just mentioning that our time for snow is running out will suddenly bring D.C. some meaningful snow accumulation after February 24 this year.

If not, well, there’s always next winter…

Correction: The original text (and the accompany graphic) indicated 2 inches of snow fell April 28, 1898 whereas it was just 0.5 inch that was measured on that date. The latest 2 inch snow in Washington, D.C. weather records occurred on April 12, 1918.

By  |  01:15 PM ET, 02/19/2013

Categories:  Latest, Local Climate

 
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