This December will finish as a warmer and wetter than average month in the Nation’s Capital for the fifth time in the last six years. Through December 30, DC’s December average temperature (combining daily high and low temperatures) is 2.1° above average. Washingtonians also exceeded the December rainfall average (3.05”) with 3.28”. December 2019 won’t finish as wet as last December (5.82”) or as warm as December 2015 (11.5° warmer than average).
DC had no measurable snowfall occurred in December
2014, 2015 and 2018. However, each of
the subsequent winters (2014-2015, 2015-2016 and 2018-2019) finished with above
average snowfall. That means there’s
good news for snow lovers in the DC Metro Area longing for appreciable
snowfall. It’s true that Washingtonians
officially saw 0.4” of snow this month, well below DC’s December average of
2.3”. However, once the calendar changes
to January, there can be a dramatic change in the weather pattern. For example, a significant dip in the jet
stream occurred in early January 2015 that coincided with the passage of a
vigorous Alberta Clipper that brought the Nation’s Capital a robust 2.4” on
January 6. What’s more, February 2015
was DC’s coldest February since 1996 and finished with 9.8” of snow.
December 2015 was DC’s warmest on record and featured
more days with highs in the 70s (three) then had lows at or below freezing
(two). It was also a wet month with rain
on nine of its final 10 days that helped it finish 1.79” wetter than
average. The first measurable snowfall
of the 2015-2016 didn’t occur until January 17 and set a record for DC’s latest
first accumulating snowfall. DC’s fourth largest snowstorm occurred a few days after that.
December 2018 was another warm and wet month with
5.82” of rain (nearly double DC’s December average of 3.05”) that helped 2018
finish as DC’s wettest year on record.
However, a significant winter storm that spanned three days brought the
Nation’s Capital 11.5” of snow the following month – DC’s largest snow event
since the record January 2016 storm.
The only colder than average December in recent years
occurred in 2017. However, the 2017-2018
winter finished with half of DC’s seasonal average of 15.4” of snow. That helps illustrate that a cold December
doesn’t always foreshadow a snowy winter, just as a warm and wet December
doesn’t portend a warm winter. Although NOAA’s
January outlook is for near average temperatures and above average precipitation
in the DC Metro Area, the right ingredients need to come together only once to
produce a significant snowfall.