D.C.’s Unusually Warm Start to November

 

The first 12 days of November were warmer than average in Washington, D.C.  Highs reached 70° or higher on 10 of those days, with a record high of 81° at National Airport on November 7.  That was D.C.’s first November day of 80° warmth since 2016.

The Nation’s Capital has averaged between three and four November days with highs in the 70s dating back to the early 1990s.  What is truly rare in D.C. during the month of November are high temperatures in the 80s.  In fact, there has been a combined total of only five such days since 1993, prior to this month.  The first 12 days of this month were so warm that D.C.’s average monthly temperature (combining daily high/low temperatures) for that period was 10.8° above average, while Dulles was 12.1° warmer than average.

While this November has gotten off to an incredibly warm start, it traditionally is a fairly cold month in the Nation’s Capital.  Four of the last five Novembers were colder than average in Washington, D.C.  In fact, November 2019 was D.C.’s coldest since 1996.  Accumulating snowfall occurred in the Nation’s Capital in November 2018, making it the first November since 1996 to do so.

Despite the string of recent colder than average November’s, D.C.’s 10 coldest November’s all occurred in 1917 or earlier.  That’s long before National Airport became D.C.’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.  Also, suburban sprawl and urbanization since the 1940s has helped make the D.C. Metro Area warmer than it was prior to World War II.  Weather records in the Nation’s Capital date back to the 1870s.

No strong correlation exists between D.C.’s November weather and what the upcoming winter season will be like.  For example, the Nation’s Capital had more snow in November 1989, then it did in January, February and March 1990 combined.  NOAA’s outlook for the next one to two weeks is for significantly colder than average weather in the D.C. Metro Area with near to slightly below average precipitation.