Feeling more like summer

 

An early fall day at the National Cathedral

Although September is the first month of meteorological fall (the three-month period of September, October and November), this September has gotten off to a very summery start in the nation’s capital. The DMV (DC, Maryland and Virginia) will continue to experience July-like heat much of this week.

More typically, September features some of the best weather of the year in the nation’s capital. Average daily high/low temperatures drop from 85°/69° on September 1 to 75°/59° by the end of the month. The amount of daylight continues to decline throughout September. Sunset will occur at 6:54 p.m. on September 30. The combination of reduced daylight and a lower sun angle contributes to the cooler average temperatures as September wears on. 

Five of DC’s 10 warmest September’s have occurred since 2005. DC’s hottest September temperature on record is 104° on September 7, 1881. Triple-digit September heat is a rarity in the nation’s capital and has occurred only four times since 1871, with none since 1980. To add to that, yesterday’s high temperature of 98° was DC’s hottest September temperature since September 7, 2023 (also 98°). By comparison, DC’s coolest September temperature is 36° from September 23, 1904.

Although Washington, D.C. averages 3.93” of September rainfall, the amount of rain can fluctuate wildly year-by-year. September can be a very wet month if decaying tropical systems bring appreciable rainfall. Such was the case with Floyd in 1999, Isabel in 2003 and Florence in 2018. This month can also be very dry in the nation’s capital. The driest September on record was in 2005 (0.11”) and the fourth driest occurred in 2019 (0.25”).

Last September featured near average temperatures and rainfall in the nation’s capital. By comparison, NOAA’s Climate Prediction Center expects this September to finish with warmer than average temperatures and near average rainfall.