November’s Warm Start

 

Yesterday felt more like late-January with a high/low of only (45°/35°) and was DC’s coldest day since March 23 (47°/41°).  This month has, nevertheless, been quite warm overall.  There have been seven days with highs in the 70s, well above the average of between three and four days.  Through November 17, DC’s average monthly temperature (combining daily high/low temperatures) is 56.7° or 4.9° above average.

Following yesterday’s cold weather and this morning’s lows in the 20s and 30s, Washingtonians are in store for a moderating trend.  Highs today will reach the 50s, while the 60s will return tomorrow and continue through the weekend.  The first half of November was exceptionally warm with a slew of records set at the three major DC Area airports, National, Dulles and BWI. 

The warmth so far this month is a welcome change of pace considering the last two Novembers have been quite cool in the Nation’s Capital – each finishing more than 3° below average.  November 2019 was actually DC’s coldest November since 1996, with a monthly average temperature of 46.1° (3.5° below average).  Last November was also DC’s first without any 70° weather in a decade.

If no more rain falls this month, then DC’s rainfall total of 3.69” since November 1 would ensures that it becomes only the second wetter than average November of the last decade.  The only other exception was November 2018, which finished as DC’s wettest on record with 7.57” of rain (compared to an average of 3.17”).  NOAA’s climate data for temperatures and precipitation is based on a running 30-year average that’s updated every decade.  The fact Washingtonians have had so many drier than average November’s over the last decade will be factored into NOAA’s updated precipitation averages when the 30-year period is updated.  Starting in January 2021, “average” weather will use the period of 1991-2020 instead of the current period of 1981-2010.

NOAA’s Climate Prediction Center expects warmer than average conditions to continue over the final third of November.  Whether or not there are any more 70° days this month, it has already been much warmer than average.  However, more above average temperatures could help make this month one of DC’s Top 10 warmest November’s on record. 

Average high temperatures fall to the low to mid-50s in the Nation’s Capital during the last week of November, compared to the low to mid-60s early in the month.  That helps explain why 70° temperatures get less and less common in the DC Metro Area as the month of November wears on.  My colleagues and I on the WUSA9 Weather team will continue to provide residents of the DC Metro Area with the latest weather forecasts.