O'Fallon Weather in September

O'Fallon in September sees high temperatures, with highs around 27°C (81°F) and overnight lows of 15°C (59°F). Rainfall is fairly high at around 102 mm (4 in) on average, so pack waterproofs just in case.

Rainfall in O'Fallon in September

Typically, about 10 days will experience rainfall, with an average of 102 mm (4 in) for the month. The rain this month tends to fall in heavier spells rather than light drizzle. When it rains, showers can be significant.

Temperature in O'Fallon in September

Temperatures in O'Fallon in September top out at 27°C (81°F) and drop to 15°C (59°F) overnight. This gives the month a fairly typical daily rhythm, with warmer afternoons and more comfortable nights. At 15°C (59°F) overnight, it can feel quite a bit cooler after dark. Worth packing something warmer for evenings, but the cooler temperatures are ideal for sleeping.

Sunshine in O'Fallon in September

The city usually sees around 235 hours of sunlight, indicating many sunny days , a great month for sightseeing.

If you prefer dry days with pleasant temperatures, October typically offers the best circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.