A Quiet September Gives Way to a Stormy October

 

Avenel Park, Potomac, Maryland

September 2022 will finish as a drier than average month in the Nation’s Capital for only the second time in the last five years.  There have been long stretches of warm and dry early-fall weather this month with ideal conditions for outdoor activities.  It will finish within 1° of average with cooler than average temperatures today, tomorrow and Friday.

The first half of September was quite warm and rainy.  Only one day was cooler than average through September 15 in the Nation’s Capital, according to NOAA.  High temperatures reached 91° on two days (September 1, September 4).  The Nation’s Capital has ranged between 2 and 9 September days in the 90s every year since 2012.  D.C. coolest temperature this month was 51° on September 24 and again this morning.

Rainfall this month has been spotty, although two days had nearly an inch of rain (September 4: 0.82” and September 11: 0.86”).  That’s accounted for most of the 1.95” of D.C.’s September rainfall.  The Nation’s Capital averages 3.93” of September rainfall according to NOAA.  Dry September’s can sometimes be followed by rainy October’s such as in 2005 when D.C.’s driest September (0.11”) was followed by its rainiest October (9.41”).  More recently, September 2019 (0.25”) was followed by a wetter than average October (6.66”), but one event doesn’t necessarily lead to another. 

Although the 2022 Atlantic hurricane season had a quiet July and August, the tropics have gotten a lot busier this month.  The D.C. Metro Area hasn’t seen any impacts from tropical systems so far this season, unlike recent September’s (2011: Tropical Storm Lee or 2018: Hurricane Florence).  However, that’s expected to change in a big way this weekend as the remnants of Hurricane Ian track northward.  Depending on the exact track, the Nation’s Capital could see appreciable rainfall as October gets underway.

A warmer and drier than average September has little bearing on what the rest of the autumn will be like in the Nation’s Capital.  Although Washingtonians have seen 90° heat as late as October 11, NOAA’s Climate Prediction Center expects near normal temperatures with above average rainfall during the first week of October – largely due to the remnants of Ian.