O'Fallon Weather Forecast

    • 70
    • 84

    Mostly Cloudy

    • 68
    • 83

    Chance Thunderstorms

    • 73
    • 90

    Chance Thunderstorms

    • 69
    • 87

    Thunderstorms Likely

    • 68
    • 85

    Slight Chance Thunderstorms

    • 74
    • 90

    Mostly Sunny

Today 15 Jun St. Clair

Partly sunny. Near steady temperature in the lower 80s. Northeast Winds around 5 Mph.

Tonight 15 Jun St. Clair

Mostly cloudy. A slight chance of Showers after midnight. Lows around 70. East Winds around 5 Mph. Chance of rain 20 percent.

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  • Temperature Forecast NOAA

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O'Fallon Temperature Statistics

June Temperature

Belleville, Scott AFB/MidAmerica Airport (4.3 miles)

  • Lowest 11 June, 2025

    58.3 °F

  • Average June

    72.4 °F

  • Highest 3 June, 2025

    85.8 °F

Climate (2020–Present)

Belleville, Scott AFB/MidAmerica Airport (4.3 miles)

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  • Average Low 2020–2025

    47.3 °F

  • Average 2020–2025

    57.1 °F

  • Average High 2020–2025

    67.3 °F
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