Summer in October?

Great Falls National Park, Great Falls, Maryland

Washingtonians enjoyed a high degree of warm and dry weather conditions during the first three/+ weeks of October.  That continues the trend of recent Octobers in the Mid-Atlantic Region.  DC residents have experienced four of their 20 warmest Octobers on record over the last decade, according to NOAA.  That includes October 2007 – DC’s warmest on record since record keeping began in 1871.

The monthly average temperature (combining daily high and low temperatures) in the Nation’s Capital is 67.3° through October 22.  That will come down over the course of the week with significantly cooler and more seasonal temperatures on tap.  However, it’s been so warm for enough of the month to put this October in the conversation among DC’s warmest.  Nine of Washington, D.C.’s 10 warmest Octobers have occurred since National Airport opened in 1941. 

The warmest temperature so far this month was 86° on October 9 and 10.  That’s the average high on August 19.  Washingtonians had six days with high temperatures of at least 80° this month, the highest such total since 2007.  Since 1993, Washingtonians have had an average of more than three such days, with an 85° October day roughly every other year.  By comparison, Washington, D.C. averaged nearly two October days with low temperatures in the 30s in that time.  Some may wonder if there is a correlation between a warmer than average October and the upcoming winter season.  The short answer is no.

Of the District’s 10 warmest Octobers, it has gone on to have a warmer than average winter six times.  Washington, D.C. also had below average snowfall in seven of the 10 winters following those warmest Octobers.  Although Washington, D.C. averages a trace of snow (less than 0.01”) in October, none has occurred since October 2011.  The last time measurable snow occurred in Washington, D.C. in October was in 1979.

If the month were to end today, it would rank as the 17^th driest October on record with 0.83” at National Airport.  However, some much needed rainfall is on the way later today and tonight.  Over the last 20 years there has been an almost even split with eight drier than average Octobers and 11 wetter than average Octobers.  For those tired of warmer than average weather, cooler and more seasonal temperatures will soon arrive in the DC Metro Area.

Warmest Octobers (Washington, D.C. weather measurements made at National Airport, DCA):

1.  67.1° (2007)
2.  65.2° (1984)
3.  64.7° (1971)
4.  64.5° (1947)
5.  64.4° (1941)
6.  63.4° (1949)
7.  63.3° (1973)
8.  63.2° (1975, 1919)
10.  63.1° (2016)

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Driest Octobers (DCA):

1.  Trace (1963)
2.  0.02” (2000)
3.  0.29” (1874)
4.  0.34” (1896, 1892)
6.  0.40” (1920)
7.  0.44” (1944)
8.  0.53” (1882)
9.  0.59” (1998)
10.  0.65” (1912)