November’s Cold and Dry First Half

NOAA's Temperature Outlook November 25 - December 1

The first half of November was cold and dry in the Nation’s Capital.  That’s in stark contrast to the way October ended.  A total of 2.99” of rain fell during the final five days of last month, while only 0.13” has occurred as of November 17.  To add to that, 14 of the first 17 days of November have been colder than average in Washington, D.C.

The warmest day so far this month was 69° on November 11, but that warmth was fleeting.  DC’s average monthly temperature through November 17 is an astounding 6.4° colder than average.  In fact, the first 16 days of November were DC’s coldest since 1995.

This month has also been quite dry compared to last November that finished as DC’s wettest.  It’s interesting to note that DC’s 10 coldest Novembers all occurred in 1917 or earlier.  That’s long before National Airport became DC’s official weather reporting site.  Prior to that, weather measurements for the Nation’s Capital were made downtown.  At that point in time, “downtown” was vastly different.  Washington, D.C. was largely undeveloped with lots of green space and little or no automobile traffic.  In other words, there wasn’t a significant urban heat island effect the way there is today.

The Potomac River plays a significant role in moderating temperatures at National Airport by helping keep them cooler in the summer and fall and warmer in the depths of winter.  Suburban sprawl and urbanization since the 1940s has helped make the DC Metro Area warmer than it was prior to World War II.  Weather records in the Nation’s Capital date back to the 1870s, but there is a big difference between temperature records at National Airport and pre-National Airport.  

There is no strong correlation between DC’s November weather and what the remainder of the winter will be like.  For example, while 11.5” of snow fell in the Nation’s Capital in November 1987, there was less snow in December 1987, February and March 1988 combined.  More snow also occurred in November 1989 than in January – March 1990 combined.  Fortunately, some milder temperatures are expected later this week with a few days of high temperatures in the 50s.  NOAA Climate Prediction Center expects near average temperatures in the DC Metro Area from November 25 – December 1.