Is October shorts or coat weather?

 

An October day in suburban Washington, D.C.

October is a transitional weather month as average temperature and the daily amount of daylight both decrease throughout the month in the nation’s capital. That’s not to say there aren’t very warm October days in the nation’s capital, much like early winter’s chill can also occur.

Given the decreasing daily amount of sunlight and lowering sun angle as October wears on, it gets harder for very warm weather to occur. That said, there has been unusually warm October weather in recent years. For example, DC’s hottest October temperature on record, 98°, occurred on October 2, 2019. To add to that, last Halloween’s high temperature of 83° was the warmest October 31 in the nation’s capital since 1950.

Over the last 30 years, the nation’s capital has averaged between three and four October days with highs in the 80s. However, 90-degree October heat is less common with only one such occurrence roughly once every four years – and none since 2019. The latest in the calendar year 90-degree heat occurred in Washington, D.C. was on October 11, 1919.

October lows in the 30s also occur on occasion in the nation’s capital. Such chilly temperatures, however, have been less common than highs in the 80s in recent decades. Washington, D.C. has averaged only between one and two October days with lows in the 30s over the last 30 years.

There hasn’t been an October temperature at or below freezing in the nation’s capital since 1992. That can be attributed in part to a warming climate, as revealed in NOAA’s updated climate averages for the period of 1991-2020. The relatively warm decade of the 2010s replaced the cooler 1980s for this update. Also, there’s a more pronounced urban heat island effect now than in past decades due to increased urbanization and automobile traffic.

DC’s warmest October’s (Source: NOAA)

1. 67.1° - 2007
2. 66.3° - 2021
3. 65.2° - 1984
4. 64.9° - 2017
5. 64.7° - 1971
6. 64.5° - 1947
7. 64.4° - 1941
8. 64.1° - 2019
9. 63.4° - 1949
10. 63.3° - 1943
11. 63.2° - 1975, 1919
13. 63.1° - 2023, 2016
15. 63.0° - 2024, 1879