O'Fallon Weather Forecast

    • 71
    • 90

    Thunderstorms

    • 69
    • 86

    Chance Thunderstorms

    • 68
    • 87

    Slight Chance Thunderstorms

    • 70
    • 88

    Mostly Sunny

    • 71
    • 90

    Mostly Sunny

    • 72
    • 92

    Mostly Sunny

Today 10 Jul St. Charles

Partly sunny. Scattered Showers and Thunderstorms in the afternoon. Humid with Highs in the upper 80s. Southwest Winds around 5 Mph, becoming northwest in the afternoon. Chance of rain 50 percent. Heat index Values up to 101.

Tonight 10 Jul St. Charles

Mostly cloudy with a chance of Showers and Thunderstorms. Near steady temperature in the lower 70s. South Winds around 5 Mph. Chance of rain 50 percent.

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  • Temperature Real-Time

O'Fallon Temperature Statistics

July Temperature

St. Louis, Spirit Of St. Louis Airport (10.6 miles)

  • Lowest 6 July, 2026

    68.6 °F

  • Average July

    81.5 °F

  • Highest 2 July, 2026

    96.7 °F

Climate (2021–2026)

St. Louis, Spirit Of St. Louis Airport (10.6 miles)

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  • Average Low 2021–2026

    46.1 °F

  • Average 2021–2026

    57.4 °F

  • Average High 2021–2026

    68.9 °F
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