What Kind of December Weather Can Washingtonians Expect ?

December is the first month of “meteorological winter” that runs through the end of February.  Average temperatures continue to fall throughout this month as DC’s coldest month, January, looms on the horizon.  Although Washingtonians have had significant snowfall and frigid temperatures historically during the month of December, occasional spring-like warmth can occur as well.

DC’s average temperatures this month range from a high and low of 52°/37° on December 1 to 44°/29° on December 31.  The coldest temperature on record in Washington, D.C. this month is -13° on December 31, 1880.  DC’s warmest December temperature on record occurred more recently on December 7, 1998 (79°).  Six of the last seven December’s have been warmer than average in Washington, D.C., including DC’s warmest December on record in 2015.

Over the last 25 years, DC has averaged one 70° day roughly four out of every five years.  That’s about the same frequency with which Washingtonians have experienced December days when high temperatures remained in the 20s.  Area residents may recall the frigid end of December 2017.  The high temperature on December 31, 2017 in the Nation’s Capital was only 23° - DC’s coldest December high temperature in more than 20 years.

The Nation’s Capital averages 3.05” of rain during the month of December.  Ten of the last 20 Decembers have been drier than average, including the last two.  DC also averages 2.3” of snow in December and snow has occurred in 18 of the last 20 December’s.  December 2009 was DC’s snowiest on record with 16.6”.  Almost all of that can be attributed to DC’s eighth largest snowstorm that occurred on December 18-19, 2009, when 16.4” of snow fell at National Airport. 

 

While DC Area residents had snow on the ground Christmas Day in 2009, it was leftover snow from the storm the week before.  The National Weather Service defines a “White Christmas” as “…at least 1 inch of snow being on the ground on December 25.”  The last time measurable snow occurred on December 25 in Washington, D.C. was in 2002 with 0.2”.

The overall weather pattern in the Nation’s Capital at the start of this December is significantly different then it was a year ago.  The first 11 months of 2017 featured eight drier than average months in Washington, D.C.  By comparison, eight of the first 11 months of 2018 have been wetter than average.  Last month became the wettest November on record in the Nation’s Capital with 7.57” of rain breaking a 141 year-old record.  

So far this month, Washingtonians have had 0.32” of rain.  The yearly total is 60.78” since January 1.  The Nation’s Capital is on the verge of setting a new record for all-time wettest calendar year.  DC’s existing record for wettest year of 61.33” was set back in 1889.  Ironically, December 1889 was also DC’s driest on record.