Can more significant snow fall — and stick — in October? Yes. On Oct. 19, 1989, six inches fell in Dayton (our greatest October snow total on record). It caused a nightmare on the roads, and the weight of snow on trees that still had leaves led to downed branches and power lines. We may not see that kind of October snowfall again in our lifetimes.
Just about as rare as snow in October is our temperature falling below 30 degrees. Over the past 10 years, that has happened three times, all in October 1997. The lowest temperature was 26, which came at the end of a unusually cool stretch. I think this is very telling. Sunny afternoons in the 70s and even low 80s are quite common in October. That setup warms the ground, or at least slows the cooling that naturally occurs this time of year. Warm ground keeps temperatures above 30 degrees, makes snow rare and almost guarantees that it will not stick, even if it falls.
Late last week and this past weekend, however, we had air about as chilly as we see in October. The temperature fell to 31 on Thursday, to 33 on Friday and Saturday, and to 30 on Sunday. A few locations Sunday morning dipped into the upper 20s.
Sunday was the coldest morning because the setup was right for temperatures to drop. Skies were clear, winds were light, and the air was bone dry. Those are the ingredients that are ripe for the ground to lose heat at night, and the air near the ground cools as a result. Typically strong winds are needed to bring cold air into the area this time of year, but any wind that lingers through the night doesn’t allow temperatures to fall as much.