August Gets Underway

August has gotten off to an active start in the Nation’s Capital with showers and thunderstorms likely on several days during the upcoming week.  That’s in addition to the anticipated impact of Tropical Storm Isaias on Tuesday.  This follows one of DC’s warmest months on record.  July 2020 finished as DC’s third warmest with a monthly average temperature of 83.9°, putting it narrowly behind July 2011 and July 2012.

Although no record heat occurred last month, the consistency of the heat was memorable.  Washingtonians experienced a record total of 28 days with high temperatures in the 90s.  The coolest temperature during all of last month was 71°.  That made July 2020 the first time an entire calendar month passed when the air temperature didn’t once fall below 70° in the Nation’s Capital.  Last month was DC’s sixth consecutive warmer than average July, and also DC’s fourth consecutive wetter than average July (6.51” or 2.78” above average). 

August is DC’s second hottest month of the year.  Average temperatures fall throughout August from a daily high/low of 88°/71° on August 1 to 84°/68° on August 31.  DC’s hottest August temperature of 106° occurred twice: August 6, 1918 and July 20, 1930.  That’s also DC’s hottest overall temperature on record.  DC’s coolest August temperature of 49° occurred three times, most recently on August 29, 1986.  

The month of August can be very wet depending on whether the DC Metro Area sees the impacts of any tropical systems.  For example, in August 2011 a weakening Hurricane Irene brought the Nation’s Capital between 2” – 6” of rain.  Forecasting the track of tropical systems can be challenging several days in advance since a shift in storm track as little as 30 miles can make a significant difference between where impacts are felt.  Tropical Storm Isaias could become a minimal hurricane once again off the southeast coast of the United States.  

DC averages 2.93” of rain in August, but that can vary from 0.55” in DC’s driest August (1962) to DC’s wettest August of 14.41” in 1928.  Over the last 20 years, there have been 11 drier than average August’s in the Nation’s Capital.  Meanwhile, 14 of the last 20 August’s have been warmer than average.  In fact, four of the last five August’s were warmer than average in Washington, D.C.

DC residents have experienced triple-digit August heat in six times since 1993, or roughly once every four to five years.  No 100° heat, however, has occurred in the Nation’s Capital since August 13 – 15, 2016.  NOAA’s Climate Prediction Center expects this August to be warmer and wetter than average in the Nation’s Capital.