Surprising Trends in DC Snowfall

 

Today is the anniversary of one of the most destructive ice storms in the Nation’s Capital.  On January 15, 1999, a bout of freezing rain caused a fairly significant ice accumulation on local roads, trees and automobiles.  That led to roughly 500,000 power outages, including 223,000 with Pepco customers alone, in what was the DC Metro Area’s largest weather-related power outage on record.  That record stood until Hurricane Isabel in September 2003, which caused over a million power outages in and around the Nation’s Capital.

As DC Area winter weather enthusiasts know, snowfall has been hard to come by over the last two years.  The last snowier than average month in the Nation’s Capital was in January 2019.  There have been several similar stretches in Washington, D.C. during the last 25 years.  For example, there was another streak of two years Washingtonians had below average snowfall from February 2011 through February 2013.

Washingtonians had 33 consecutive months of below average snowfall from February 2000 through November 2002.  Although the Nation’s Capital only averages measurable snowfall from November through March, going two or more consecutive winters without a single month of above average snowfall is unusual.  Washington, D.C. also set a record for longest stretch without a half an inch of snow on a calendar day eclipsing the previous record of 693 days that ended January 7, 1999.  The last time at last a half an inch of snow occurred in the Nation’s Capital was on February 20, 2019 (2.6”).

Washingtonians average 5.6” of snow during the month of January, using National Weather Service data from 1981-2010.  It’s possible that while a single storm could bring double that amount of snow, the entire winter could still finish with below average snowfall.  Such was the case during the 1998-1999 winter season when March was DC’s snowiest month with 8.7”, more than six times the monthly average (1.3”).  Despite being a very snowy March, the 1998-1999 winter finished with 11.6” of snow, or 3.8” below the seasonal average.

Similarly, the 2015-2016 winter season that would have finished with less than a third of DC’s annual snowfall average without the January 2016 blizzard.  These facts illustrate that while the Nation’s Capital hasn’t had much snow during the last two years, the weather pattern can change relatively quickly to create favorable conditions for a respectable snow event. 

The 2020-2021 winter season is poised to break a record that was set recently during the 2015-2016 winter.  DC’s existing record for latest first accumulating snowfall at National Airport is January 17, 2016 (0.3”).  Although a trace of snow – too little to measure – occurred on December 16, 2020, no accumulating snowfall has occurred yet this winter in Washington, D.C.  No accumulating snow is expected through this weekend either.