December Snow and its Impact on Temperatures

Washingtonians have seen their fair share of snow in December.  That’s not unusual since December is the third snowiest month of the year in the Nation’s Capital.  Saturday’s snow totals of 1.5” at National Airport and 4.0” at Dulles Airport were the first measurable December snowfall to occur since 2013.  Washington, D.C. averages 2.3” of December snow at National and 3.5” at Dulles. 

DC Area residents have had measurable December snow in 11 of the last 17 years.  DC’s snowiest December on record occurred in 2009 with DC’s 8^th largest snowfall on record.  It’s interesting that some of December’s coldest days have come immediately following a fresh snowfall.  For example, the snowiest December 5 on record occurred in 2002, with 6.1” at National and 6.2” at Dulles.  Following the record snowfall, combined with clear skies and calm winds, Dulles Airport experienced record cold on three consecutive mornings from December 6 – 8, 2002.  

Although no record December cold has occurred in Washington, D.C. since 1989, there have been some bitterly cold December days.  Washingtonians had such a day last year on December 16, with a high/low temperature of only 30°/17°.  According to the National Weather Service, the last time the Nation’s Capital experienced consecutive December days with high temperatures at or below freezing was December 13 – 14, 2005 (32°, 26°).  Longtime residents may recall that temperatures remained at or below freezing on five consecutive days in the Nation’s Capital from December 26 – 30, 1993, and on four consecutive days from December 10 – 13, 1995.

Several days of below average are on tap this week for the DC Metro Area, with several chances for flurries and scattered snow showers.  Moreover, tomorrow is shaping up to be one of DC’s coldest December days in several years.  The last time high temperatures remained at or below freezing in Washington, D.C. prior to December 15 was on December 13, 2005 (32°).  The last time high temperatures in Washington, D.C. remained under 30° during the first half of December was December 14, 2010 (29°).

While National Airport hasn’t had any record December cold since 1989, there have been 11 record highs in the month of December over just the last 20 years.  That’s in addition to having measurable December snow in roughly two-thirds of the Decembers since 2000.  By comparison, the more rural Dulles Airport has had a combined nine record low and record high/low December temperatures over the last 20 years.  No strong direct correlation exists, however, between periods of cold and snowy December weather and the winter season as a whole in the DC Metro Area.