In October, O'Fallon typically sees daytime highs of 21.0°C and overnight lows around 7.2°C. Compared to the annual average high of 18.9°C, October runs +2.1°C.
October in O'Fallon averages a daytime high of 21.0°C and an overnight low of 7.2°C.
October runs +2.1°C compared to O'Fallon's annual average high of 18.9°C, ranking #6 of 12 months by warmth.
Plan for daytime highs near 21.0°C and cooler evenings around 7.2°C.