O'Fallon Weather Forecast

    • 24
    • 46

    Mostly Sunny

    • 10
    • 39

    Mostly Cloudy

    • 3
    • 14

    Mostly Cloudy

    • 8
    • 13

    Chance Snow

    • -1
    • 19

    Partly Sunny

    • 5
    • 17

    Mostly Sunny

    • 14
    • 29

    Partly Sunny

Today 21 Jan St. Charles

Sunny. Highs in the mid 40s. West Winds 10 to 15 Mph with Gusts up to 25 Mph.

Tonight 21 Jan St. Charles

Mostly clear this Evening, then becoming partly cloudy. Lows in the mid 20s. West Winds 10 to 15 Mph, becoming northwest 5 to 10 Mph after midnight.

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  • Temperature Real-Time

O'Fallon Temperature Statistics

January Temperature

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

  • Lowest 18 January, 2026

    8.1 °F

  • Average January

    38 °F

  • Highest 6 January, 2026

    68 °F

Climate (2021–Present)

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

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  • Average Low 2021–2026

    45.9 °F

  • Average 2021–2026

    57.1 °F

  • Average High 2021–2026

    68.4 °F
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