O'Fallon Weather Forecast

    • 49
    • 75

    Sunny

    • 59
    • 77

    Rain Showers Likely

    • 66
    • 89

    Chance Thunderstorms

    • 66
    • 89

    Chance Thunderstorms

    • 71
    • 88

    Chance Thunderstorms

    • 67
    • 90

    Rain Showers Likely

Today 13 May St. Charles

Sunny. Highs in the mid 70s. Northwest Winds 10 to 15 Mph with Gusts up to 25 Mph.

Tonight 13 May St. Charles

Clear. Lows in the upper 40s. North Winds 5 to 10 Mph with Gusts up to 20 Mph in the Evening, becoming light and variable.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

O'Fallon Temperature Statistics

May Temperature

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

  • Lowest 7 May, 2026

    36.6 °F

  • Average May

    57.9 °F

  • Highest 4 May, 2026

    81.6 °F

Climate (2021–Present)

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

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  • Average Low 2021–2026

    46 °F

  • Average 2021–2026

    57.4 °F

  • Average High 2021–2026

    68.8 °F
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