Is December’s Weather an Accurate Predictor for Winter?

NOAA's Temperature Outlook for December 2016

Washingtonians can expect an average of 2.3” of snow in December.  Although less snow than what January and February average, December is the first month of meteorological winter and can set the trend for the entire season.  There have been winters when December has been warm and wet that have gone on to be snowier than average, while there have been winters when December was the coldest and snowiest month of the entire season.

Just last year there was a 180-degree turnaround between the warmest December on record in the Nation’s Capital and January 2016, which was more than a degree colder than average.  Last January also saw 18.8” of snow that made it the snowiest January in Washington, D.C. since 1996.  The majority of that fell during the fourth largest snowstorm on record on January 22-23, when 17.8” fell at National Airport.

Last winter ended up being the third consecutive snowier than average winter in Washington, D.C.   Ironically, this happened even though a strong El Nino event contributed to making the 2015-16 winter more than three degrees warmer than average in the Nation’s Capital.  The combination of one record snowstorm during a warmer than average winter shows that one significant storm can make an entire season snowier than average.  The last time the Nation’s Capital had three consecutive winters with at or above average snowfall was 1985 – 1988.

The 1989-90 winter saw the opposite extreme from last winter.  December 1989 was the coldest in the Nation’s Capital since 1917, when the monthly average temperature was also 27.9 degrees.  A total of 12.5” of snow fell in November and December 1989, making it the only year that Washington, D.C. had both a white Thanksgiving and Christmas.  However, once the calendar changed to 1990 the weather changed dramatically in the Mid-Atlantic Region.  January and February were both appreciably warmer than average.  So while the 1989-1990 winter season finished within 0.1” of average snowfall (15.3” vs. 15.4”), over 80% of that occurred in November and December.

NOAA’s outlook for this month calls for a slight chance of above average temperatures and precipitation.  However, for the next one to two weeks its outlook is for cooler than average temperatures.  My colleagues and I on the WUSA9 weather team are tracking the coldest weather of the season which is poised to arrive by the end of the week.  Although the arctic front may bring a few flurries and some light snow showers on Thursday, Washingtonians longing for significant snow will have to wait.