December’s First Half

DC’s weather during the first half of December has been remarkably close to average.  Temperatures through December 18 were within 0.6° of the average.  That’s much closer than November, which finished 3.5° colder than average.  And it’s also much cooler than last December which finished 3.8° warmer than average.

The warmest temperature so far this month was 60° on December 10.  The coldest temperature so far this month in DC was 27° on December 18.  What has stood out so far this month has been the relatively high number of rainy and gloomy days.  Ten of the first 18 days of December have produced measurable rainfall in the Nation’s Capital.  While than half of DC’s December days so far have been rainy, Washingtonians have officially had only 2.42” of rain through December 18.  That’s not an unusually high amount.  DC residents had 3.76” of rain for the same period last December.  The Nation’s Capital averages 3.05” for the entire month of December.  

Accumulating snowfall also occurred two days this month with a combined total of 0.4”.  That’s not a significant amount of snow by any stretch, considering DC averages 2.3” for the month.  It is noteworthy, though, since accumulating snowfall has now occurred in the Nation’s Capital in 11 Decembers since 2002.  Today also marks the tenth anniversary of DC’s largest December snowstorm when 16.4” fell on December 18-19, 2009.

Fortunately, for those people tired of the recent stretch of wet weather, there has been a shift in the weather pattern.  NOAA’s Climate Prediction Center expects the next six to 10 days to be drier than average in the Mid-Atlantic Region through December 29.  There is no rain or snow on the WUSA9 7-day weather forecast either, as we expect dry conditions through Christmas Day.

While that’s good news for travelers and last minute holiday errands, it’s not for DC Area residents longing for a White Christmas.  Snow on Christmas in the Nation’s Capital is a relative rarity with only four White Christmas’s in the last 30 years.  Some other cities that see snow on Christmas more frequently than DC include Minneapolis, Chicago, Buffalo, and Albany.

An important distinction is that a “White Christmas” can mean two things.  New snowfall can occur on Christmas Day or snow from a previous storm could linger on the ground on December 25.  The latter tends to occur during very cold Decembers such as in 1989 and 2009.  December 1989 was a very cold and snowy month with 9” of snow in the Nation’s Capital, but the rest of the 1989-1990 winter was mild with below average snowfall (DC averages 15.4” of snow annually).  By comparison, the cold and snowy December 2009 was just a harbinger of what became DC’s snowiest winter on record in 2009-2010.  DC’s last White Christmas was in 2009.