December’s Cold and Dry Start in DC

NOAA Expects a Moderating Trend Next Week

Early December has been colder and drier than average in the Nation’s Capital, with a near miss by a major snowstorm.  Through December 11, this month has been 2.2° colder than average.  It has also had below average rainfall so far.  That’s significant since Washington, D.C. hasn’t yet broken its longstanding record for wettest year.  The Nation’s Capital has sat with an annual total of 60.78” of rain since December 3.  That’s only 0.55” away from the 1889 record of 61.33”.  But an expected storm on Friday afternoon continuing into the weekend is expected to make 2018 DC’s wettest year on record. 

In the meantime, area residents have been fortunate to enjoy a dry stretch of weather not seen in some time.  Last week was DC’s first dry work week (Monday, December 3 through Friday, December 7) since July 9 through July 13.  DC’s dry streak will reach 11 consecutive days because it will remain dry in the Nation’s Capital until Friday.  That would be DC’s longest dry stretch since a 22-day stretch from September 15 – October 6, 2017.

The major local weather story this month will likely be that the Nation’s Capital has set a new record for all-time wettest year.  DC weather records date back to 1871 and are kept by NOAA.  There are some parallels between December 1889 – the final month of the current record holder for DC’s wettest year – and December 2017.  Despite being a very wet year prior to December 1, 1889 had the driest December on record in the Nation’s Capital with only 0.19” of rain.  By comparison, last December was DC’s fifth driest with only 0.5” of rain.

As if DC setting a new record for wettest year isn’t impressive enough, there is something else that makes all the rain this year even more noteworthy.  Prior to April 2018, Washingtonians had been languishing in an extended period of drier than average weather.  From August 2015 through March 2018, the Nation’s Capital had accrued a rainfall deficit of 16.42”.  However, during the seven-month period from April 2018 through November 2018, DC had a rainfall surplus of 25.03” that more than wiped out that deficit.

This month’s colder than average start in the DC Metro Area is expected to come to an end as NOAA expects milder than average temperatures to arrive early next week and continue through Christmas.  That means the odds are against having a White Christmas this year in the Nation’s Capital.