O'Fallon Weather Forecast

    • 20
    • 38

    Mostly Cloudy

    • 26
    • 34

    Partly Sunny

    • 39
    • 52

    Mostly Cloudy

    • 27
    • 47

    Mostly Cloudy

    • 19
    • 37

    Mostly Cloudy

    • 9
    • 26

    Partly Sunny

Today 7 Dec St. Charles

Cloudy with a slight chance of drizzle. Highs in the upper 30s. Temperature falling into the lower 30s in the afternoon. West Winds 5 to 10 Mph, becoming north 10 to 15 Mph in the afternoon.

Tonight 7 Dec St. Charles

Mostly cloudy with a chance of Sprinkles. Near steady temperature in the upper 30s. South Winds around 5 Mph.

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O'Fallon Temperature Statistics

December Temperature

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

  • Lowest 4 December, 2025

    12 °F

  • Average December

    24.2 °F

  • Highest 3 December, 2025

    37.9 °F

Climate (2020–Present)

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

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  • Average Low 2020–2025

    46 °F

  • Average 2020–2025

    57.1 °F

  • Average High 2020–2025

    68.2 °F
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