O'Fallon Weather Forecast

    • 67
    • 93

    Mostly Sunny

    • 72
    • 95

    Rain Showers

    • 67
    • 81

    Rain Showers

    • 54
    • 82

    Rain Showers Likely

    • 39
    • 64

    Breezy

    • 38
    • 62

    Sunny

Today 12 Oct St. Clair

Sunny. Near steady temperature in the lower 90s. Southwest Winds 10 to 15 Mph.

Tonight 12 Oct St. Clair

Mostly clear. Lows in the upper 60s. Southwest Winds 5 to 10 Mph.

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O'Fallon Temperature Statistics

October Temperature

Belleville, Scott AFB/MidAmerica Airport (4.3 miles)

  • Lowest 6 October, 2026

    45.7 °F

  • Average October

    66.7 °F

  • Highest 1 October, 2026

    92.3 °F

Climate (2021–2026)

Belleville, Scott AFB/MidAmerica Airport (4.3 miles)

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  • Average Low 2021–2026

    48 °F

  • Average 2021–2026

    58 °F

  • Average High 2021–2026

    68.2 °F
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