O'Fallon Weather in October

The climate in O'Fallon during October can be summarized as mild and reasonably dry.

October is in the fall / autumn in O'Fallon and is typically the 6th warmest month of the year. Daytime maximum temperatures average around 20°C (69°F), whilst at night 8°C (46°F) is normal.

On average October is the 4th driest month of the year in O'Fallon with around 71mm 2.8 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 9 days, although this may vary considerably.

On the flip side this corresponds to an average of 7.4 hours of sunshine per day.

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in O'Fallon in October 2025.