DC’s unofficial start to winter

 

Winter gets underway in December

November 2023 finished as a slightly cooler and drier than average month in the nation’s capital.  Last month’s average temperature finished 0.3° cooler than average.  With the exception of November 21 (DC’s rainiest day in more than a year with 2.14”), it was a dry month.  Despite the heavy rain shortly before Thanksgiving, last month still finished with 2.51”, or 0.40” below average.

Meteorological winter officially got underway on December 1 and continues through the end of February.  Average daily temperatures fall throughout December, according to NOAA.  DC’s average high/low temperatures range from 53°/38° on December 1 to 44°/30° on December 31.  DC’s warmest December temperature on record is 79° (December 7, 1998), while its coldest December temperature is -13° (December 31, 1880).  Seven of the last 10 Decembers have been warmer than average in Washington, D.C.

The nation’s capital averages 3.41” of rain in December.  Washingtonians can also expect an average of 1.7” of December snowfall (2.8” at Dulles Airport).  However, nine of the last 10 Decembers have had below average snowfall, with 2017 being the lone exception.  DC’s wettest December (7.56”) occurred in 1901 and driest (0.19”) in 1889.  By comparison, DC’s snowiest December occurred in 2009 with 16.6” (due to one of D.C.’s largest winter storms on record).  That was also the last time the nation’s capital had a white Christmas.

December’s weather can have wide fluctuations from one year to the next.  The right ingredients need to come together only once to produce a large winter storm such as what happened in December 2009.  However, in this El Nino winter, my colleagues and I on the WUSA9 Weather Team are expecting above average snowfall.  Many of DC’s snowiest winters have occurred during El Nino winters.  Last winter had only 0.4” of snow in the nation’s capital, well below the seasonal average of 13.7”, so almost any amount of snow would seem like a lot by comparison.  Washingtonians haven’t had a snowier than average winter since 2018-2019.

While the prospect of rain will continue throughout the weekend, no significant wintry precipitation is expected for the D.C. Metro Area.  In fact, NOAA’s Climate Prediction Center expects a pattern change with above average temperatures to arrive by the middle of December.  That would follow the colder than average final week of November.