What Does December have in Store?

NOAA's Temperature Outlook for December 2015

Now that Washington, D.C.’s 5^th warmest November is in the rear view mirror, it’s a good time to look ahead to December.  December marks the start of “meteorological” winter, which runs through the end of February.  Unlike the astronomical seasons that revolve around the solstices and equinoxes, the meteorological seasons break up the year into four equal three month segments.

Average temperatures fall throughout the month in Washington, D.C. with an average high of 52 degrees on December 1.  However, that falls to 44 degrees by the end of the month.  The warmest temperature on record during the month of December in the Nation’s Capital is 79 degrees (that occurred on December 7, 1998).  The coldest temperature on record this month occurred on December 30, 1917 when it was 9 degrees.  According to the National Weather Service, Washington, D.C. averages 3.05” of rain in December along with 2.3” of snow. 

Last December was four degrees warmer than the monthly average temperature (combining daily highs and lows) of 39.7 degrees in the Nation’s Capital.  However, a warmer than average December has no bearing on what the rest of the winter will feature.  Despite the mild December last year, last winter ended up being colder than average in the Mid-Atlantic Region.  However, NOAA’s temperature outlook for this month is for milder than average temperatures across a large portion of the eastern United States – especially from the Great Lakes Region to the Mid-Atlantic and Northeast. 

Above average rainfall is expected this month which can be largely attributed to the strong El Nino event that’s developed.  Given the presence of El Nino, the entire winter has a higher likelihood of being warmer and wetter than average in this part of the country.  Some may wonder what this means for December snowfall in the Mid-Atlantic Region.  The last two El Nino’s to occur that rival the intensity of the current El Nino occurred in 1982-1983 and 1997-1998.  While measureable snow occurred in the Nation’s Capital in December 1982 (6.6”), no measureable snow occurred in December 1997. 

So while the majority of the month is poised to be warmer than average, that doesn’t rule out the possibility of some snowfall.  It’s just less likely than in other Decembers.  Snow lovers shouldn’t fret, though, because Washingtonians have seen slightly more snowfall than average in December since 2000.  In that time, National Airport has averaged 2.7” of snow (vs. their December average of 2.3”) while Dulles Airport has averaged 4.3” in December during the same 14 year time period (vs. their monthly average of 3.5”).