Feeling Like Fall

 

The coolest weather of the early fall season has arrived following the rain from the remnants of Hurricane Sally.  Not only will high temperatures remain in the 60s into next week, but low temperatures will range from the 40s in the suburbs to the 50s within city limits.  That’s more characteristic of mid-October than mid-September.  By comparison, DC’s average high temperature both today and tomorrow is 78°. 

Having three consecutive September days with highs in the 60s is rare in the Nation’s Capital.  You have to go back to 1995 to find the last time Washingtonians had four consecutive September days with high temperatures below 70°.  Despite the warm start to September 2020 with highs in the 90s on two of its first four days, temperatures have been much closer to average since then. 

Despite cooler than average weather this weekend, NOAA’s Climate Prediction Center expects warmer than average temperatures to return for much of the final week of September.  That said, having only two 90° days this month would be DC’s fewest total since 2011 when there weren’t any 90° September days.

Fortunately, there will also be an extended period of dry weather in the Nation’s Capital following what has been an exceptionally rainy period.  A total of 19.72” of rain occurred in Washington, D.C. between July 1 and September 18.  That’s 10.91” above average for the period and has produced a year-to-date rainfall total of 40.33”.  DC’s averages 39.74” of rain during the entire year, so any additional rainfall would push 2020 even further above average. 

Since July 1, there have been a total of six days with at least an inch of rain.  That includes three days with at least 2” of rain in the Nation’s Capital that set daily rainfall records (July 7, August 4 and September 10).  While Hurricane Isaias was responsible for DC’s record rainfall on August 4, the rainfall on the other two dates was the result of slow-moving thunderstorms.

Measurable rainfall occurred in the Nation’s Capital on 36 of the 80 days between July 1 and September 18.  Despite being significantly wetter than average, both July and August were much warmer than average.  September 2020 has also been wetter than average, but unlike the last two months should finish within 1° of average.  DC Area residents should take advantage of the ample sunshine, fall-like temperatures and dry weather for much of the upcoming week.