How Does August 2020 Measure Up ?

If it seems like August has been a wet month, there’s good reason.  There have been 16 days this month with measureable rainfall in the Nation’s Capital which produced a total of 8.33” (5.58” above average).  A large portion of that is attributed to the two tropical systems that impacted the DC Metro Area.

Category 1 Hurricane Isaias made landfall in North Carolina on August 3 and quickly moved northward.  It brought a significant amount of rain and severe weather to the DC Metro Area.  What’s more, Isaias spawned roughly three dozen tornadoes in the United States.  Record-setting rainfall also occurred at both National and Dulles Airports on August 4.  Washington, DC had a combined rainfall total of 3.01” during the first four days of August – more than DC averages (2.93”) during the entire month.

The middle of the month was also wet in the DC Metro Area.  There was measurable rainfall on six consecutive days, from August 12 – August 17, with widespread showers and thunderstorms each day.  While a total of 2.29” of rain occurred in that time in DC, it was even wetter in Baltimore with 6.06” at BWI Airport.  In fact, this month is poised to finish as Baltimore’s fourth wettest August with 11.69” as of August 29.  With more rain in the forecast tomorrow, Dulles Airport could finish with its third wettest August.  On top of everything, the remnants of Hurricane Laura brought more rainfall to the DC Metro Area yesterday. 

August 2020 will finish as a warmer than average month in the Nation’s Capital for the fifthteenth time in the last 20 years.  While this month’s total of seven 90° days is below DC’s average of roughly 10 such days, what’s made the difference is how warm overnight low temperatures have been.  Low temperatures remained in the 70s on 22 of the first 28 days of August and that’s unusual.  In fact, the Nation’s Capital set a record for longest stretch of consecutive days temperatures remained 70°/+ from June 27 – August 15. 

Temperatures today will be near average with highs in the mid-80s, but will be below average tomorrow with highs near 80° and the prospect of more rain.  Nevertheless, DC will finish August 2020 with a monthly average temperature (combining daily high and low temperatures) more than a degree above average.  DC’s warmest temperature this month was 93° on August 27 and August 28, while the coolest temperature was 66° on August 16 and August 17.

The outlook for September 2020 from NOAA’s Climate Prediction Center is for warmer than average temperatures in the DC Metro Area with a near average amount of rain.

DC’s Ten Wettest August’s (Source: NOAA)

1.  14.41” (1928)
2.  14.36” (1906)
3.  14.31” (1955)
4.  12.93” (1875)
5.  9.91” (1933)
6.  9.75” (1905)
7.  9.49” (1942)
8.  9.17” (1967)
9.  9.00” (1948)
10.  8.92” (2011)