Dramatic DC Weather

Friday’s high temperature of 78° was DC’s warmest temperature since it was 83° on October 11, 2018.  Although it was significantly warmer than DC’s average high temperature on March 15 of 56°, Washingtonians fell short of breaking yesterday’s record high of 82°.

Once the cold front passed through last night, there was a precipitous drop in both temperature and relative humidity.  For example, at National Airport the winds were SW at 13 MPH with a temperature and dewpoint temperature of 70° and 59°, respectively, at 9:00 PM last night.  However, by 10:00 PM the winds were NW at 18 and gusting to 26 MPH.  Consequently, the dewpoint temperature had dropped to 36° and the temperature began to fall.  The significant drop in the dewpoint led to a steep drop in relative humidity from 68% to 29% between 9:00 PM and 10:00 PM last night.  

Washingtonians have averaged four days in March with high temperatures in the 70s since 1993.  The highs of 75° and 78° on March 14-15 were the first case of consecutive high temperatures in the 70s since November 1-2, 2018.  Since the cold front passed through the Nation’s Capital last night, temperatures fell from 70° at 10:00 PM to 49° by 5:00 AM.  Yesterday’s low temperature of 57° at National Airport didn’t occur until 11:59 PM.  That prevented DC residents from setting a new record high-low temperature for March 15.  The existing record for March 15 remains 60° from 1990.  

A “high-low” or “max-min” temperature means the low temperature on a particular day was unusually warm.  There are parallels between March 15, 2019 and March 15, 2014.  The high temperature in the Nation’s Capital on March 15, 2014 was 70°.  However, DC residents had a frigid St. Patrick’s Day with a high temperature of only 32° on March 17, 2014.  That coincided with 7.2” of snowfall from March 16-17.  By comparison, high temperatures this weekend will remain in the 50s.  

Weather enthusiasts are generally happy with the month of March as there’s often something for everyone.  Measurable March snowfall has occurred in DC in seven consecutive March’s, dating back to 2013.  At the same time, Washingtonians can also expect early summer-like warmth in March.  DC’s warmest March occurred relatively recently in 2012 and featured four days with high temperatures in the 80s and no temperatures at or below freezing.