December 2021: Unusually Warm and Dry in the Nation’s Capital !

 

December 2021 has been a memorable weather month and will finish as one of D.C.'s warmest and driest on record.  It will also be the first December to be both warmer and drier than average since 2012.  There’s been ample opportunity for outdoor activities such as dining al fresco or hiking, with or without your dog.

This month's average temperature (combining daily high/low temperatures) is 47.2° through December 29, more than 5° above average.  There were 10 days this month with high temperatures of at least 60° (including two days in the 70s).  D.C.'s high temperatures of 70° on December 6 and 11 gave Washingtonians their first taste of 70° December warmth since 2015.  This month has had more days with high temperatures in the 60s (eight) than lows at or below freezing (six) and will finish as D.C.’s second warmest behind only 2015.

It has also been a very dry month with only 0.45" of rain as of December 29.  While there have been a lot of cloudy and damp days, very little rain has fallen with measurable rainfall on only six days.  That's in addition to seven days with a "trace" of rain, or too little to measure.  December will finish without any accumulating snowfall in the Nation’s Capital for the sixth time in the last eight years.  

December's dry weather continues the dominant weather trend in the Nation's Capital during the final three months of 2021.  D.C. has accrued a rainfall deficit of 5.11" since October 1.  That has led to "abnormally dry" conditions for much of the D.C. Metro Area, with moderate drought conditions for much of central and southern Virginia based on the most recent Drought Monitor Index.  Despite the dry autumn, 2021 will still finish with a modest rainfall surplus of more than 2".  That's largely due to how rainy August was with 9.07", nearly triple D.C.'s August average of 3.25".

Some may wonder what a warm and dry December means for the rest of the winter.   Warmer and drier than average weather over a month isn't a reliable indicator of what an entire season will be like.   For example, December 2015 was D.C.’s warmest on record.  However, the epic January 2016 blizzard occurred a few weeks later.  The right ingredients only need to come together once to produce appreciable snowfall.

D.C.’s Driest December’s  (Source: NOAA)

1.  0.19” (1889)
2.  0.22” (1953)
3.  0.30” (1898)
4.  0.47” (1965)
5.  0.50” (2017)
6.  0.65” (1980)
7.  0.71” (1937)
8.  0.85” (1979)
9.  0.97” (1873)
10.  1.07” (1925)

D.C.’s Warmest December’s (Source: NOAA)

1.  51.2° (2015)
2.  45.6° (1984, 1889)
4.  45.5° (2001, 1982, 1971)
7.  45.4° (2012)
8.  45.0° (2011, 1923)
10.  44.5° (1990)

Weather Quiz

 

Prior to this month, when was the last time the Nation’s Capital had a warmer and drier than average December? 

A)  2017

 

B)  2015

C)  2012

D)  2001

Unusually Dry and Warm December

 

NOAA's 6 - 10 Day Temperature Outlook

December has gotten off to an unusually warm start in the Nation’s Capital.  There were six days with highs of at least 60° at National Airport, compared to only three days when temperatures fell to 32° or colder.  Temperatures for the first two-thirds of the month were 5.6° warmer than average.

Nine of the last 10 Decembers were warmer than average in Washington, D.C.  What’s made this month unusual is how warm the first few weeks of December have been.  For the first time since 2015 Washingtonians enjoyed 70° warmth not once but twice this month.  Two record high-low temperatures were also set at National Airport.  NOAA’s day temperature outlook calls for an above average chance for more warmer than normal temperatures in the D.C. Metro Area through December 30.

This month has also been drier than average, with only 0.17” of rain as of December 20.  That’s not good news for the Nation’s Capital following a drier than average October and November.  A total of 4.42” of rain fell in Washington, D.C. since October 1, or less than half of average for that time. Consequently, the latest Drought Monitor Index shows “Abnormally Dry” conditions for much of central Maryland and Virginia, including the District of Columbia.  While the Nation’s Capital has a rainfall surplus of 2.93” for 2021 as a whole, the three-month period dating back to October 1 has been unusually dry. 

NOAA’s Climate Prediction Center expects “Near Normal” rainfall in the Nation’s Capital through the end of the year.  However, that wouldn’t be enough to prevent this month from finishing as one of D.C.’s driest on record.  This combination of warm and dry weather isn’t good news for D.C. Area winter weather enthusiasts hoping for a White Christmas.  La Nina winters, such as this one, often feature near to slightly warmer than average temperatures with near to slightly drier than average conditions in the Nation’s Capital.

D.C.’s Driest December’s  (Source: NOAA)

1.  0.19” (1889)
2.  0.22” (1953)
3.  0.30” (1898)
4.  0.47” (1965)
5.  0.50” (2017)
6.  0.65” (1980)
7.  0.71” (1937)
8.  0.85” (1979)
9.  0.97” (1873)
10.  1.07” (1925)