2018 Reaches Uncharted Territory

NOAA's Temperature Outlook for Christmas Week

Having broken DC’s longstanding record for wettest year on December 15, any additional rain before the end of the year will only pad the new record.  The old record for wettest year was set in 1889 (61.33”) and ironically featured DC’s driest December on record (0.19”).  With 3.76” of rain through December 17, December 2018 this month has already exceeded its average of 3.05”.  Since January 1, a total of 64.22” of rain has occurred in the Nation’s Capital.

DC will finish 2018 with a remarkably long and wet stretch of weather, with eight of the final nine months of the year wetter than average.  With the exception of October, every month since April has been wetter than average and this year’s rainfall has been spread out fairly evenly over much of the year.  May 2018 was DC’s sixth wettest on record, July 2018 was DC’s fourth wettest, September 2018 the fifth wettest and last month was DC’s wettest November on record.

That’s unlike some past years that have been wetter than average, but the majority of the rainfall was concentrated around a particular weather event.  For example June 1972 was DC’s third wettest on record due to the flooding rainfall from the remnants of Tropical Storm Agnes.  Meanwhile, September 1999 was DC’s fourth wettest September on record due the remnants of Hurricane Dennis followed by Hurricane Floyd.  August and September 2011 were a combined 11.11” wetter than average in Washington, D.C., largely the result of former Hurricane Irene and Tropical Storm Lee.  By comparison, the DC Metro Area has had above average rainfall over a long period of time this year and that makes 2018’s record more impressive.

With Christmas a week away some may wonder what the odds are for a White Christmas in the Nation’s Capital.  The National Weather Service defines a “White Christmas” as having “…at least 1 inch of snow on the ground on December 25.”  The last time there was snow on the ground in Washington, D.C. on Christmas Day was in 2009.  That was the result of the record December 18-19 snow event.  Washingtonians haven’t had actual snowfall on Christmas Day since 2002 (0.2”).

Washingtonians have already had the first measurable snowfall of the season with 1.4” on November 15.  Unfortunately for snow lovers in the DC Metro Area, the weather pattern is not favorable for any snow on Christmas this year.  NOAA’s temperature outlook for December 23 – 27 is for near average temperatures in the DC Metro Area along with near to slightly below average precipitation.  The average high/low temperatures in Washington, D.C. on December 25 are 44°/30°.