Weather To Be Thankful For?

 

DC Area Snowfall, November 15, 2018

 
October was a warmer and wetter than average month in the Nation’s Capital.  While no 90° heat occurred, unlike the two previous Octobers, Washingtonians have grown accustomed to above average temperatures.  While the past four consecutive October’s have been warmer than average, that’s had little bearing on November’s weather in the DC Metro Area.

November is a variable weather month in the Nation’s Capital as the transition towards winter continues.  Average daily high/low temperatures drop from 63°/45° on November 1 to 52°/37° by month’s end.  November is the third and final month of “meteorological fall.”  Consequently, there are occasionally some very warm days, but more often than not there are chillier, winter-like days as December draws closer.  DC’s warmest November temperature on record is 86° that occurred on November 1, 1974, while DC’s coldest November temperature of 11° occurred on November 30, 1929.

While five of the last eight have been cooler than average in DC, each of the subsequent Decembers were at least 2.5° warmer than average.  That helps illustrate how November temperatures aren’t a reliable indicator of what kind of December will ensue. 

DC averages 0.5” of snow during the month of December.  However, accumulating snow has become a rarity in the Nation’s Capital in November with only four such occurrences over the last 30 years.  A daily record 1.4” of snow occurred at National Airport on November 15, 2018 and that was the first time DC residents experienced accumulating November snowfall since 1996.  Prior to 2018, the last time Washingtonians saw an inch or more of November snowfall was in 1989.  Some longtime DC residents might recall the largest November snowstorm remains the 1987 Veteran’s Day snow event when 11.5” fell. 

Weather averages are maintained by the National Weather Service and are updated every decade.  This is the final year that weather averages will use the 30-year period of 1981-2010.  Starting in January, weather averages will be updated to reflect the 30-year period of 1991-2020.  Since accumulating snowfall has become increasingly rare in the Nation’s Capital during the month of November, I expect a decrease in the monthly average of 0.5”.

November’s average rainfall average is 3.17” in Washington, D.C.  However, nine of the last 10 have been drier than average.  November 2018 was, however, the one exception.  Not only was it DC’s snowiest November since 1989, but also DC’s rainiest November on record with 7.57”.  November 2020 has gotten off to a rainy and chilly start, with windy and colder than average weather today.  But, NOAA’s monthly outlook calls for warmer than average temperatures this month combined with near average precipitation in the DC Metro Area.