Saint Charles Weather Forecast

    • 64
    • 84

    Becoming Sunny

    • 69
    • 87

    Mostly Sunny

    • 64
    • 86

    Slight Chance Thunderstorms

    • 63
    • 83

    Partly Sunny

    • 65
    • 82

    Slight Chance Thunderstorms

    • 69
    • 86

    Slight Chance Rain Showers

    • 67
    • 88

    Partly Sunny

Today 20 Aug St. Charles

Partly sunny. Near steady temperature in the lower 80s. North Winds 5 to 10 Mph.

Tonight 20 Aug St. Charles

Mostly clear. Patchy fog after midnight. Lows in the lower 60s. Northeast Winds around 5 Mph.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Saint Charles Temperature Statistics

August Temperature

St. Louis Lambert International Airport (6.2 miles)

  • Lowest 3 August, 2026

    66.9 °F

  • Average August

    81.4 °F

  • Highest 11 August, 2026

    96.7 °F

Climate (2021–2026)

St. Louis Lambert International Airport (6.2 miles)

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  • Average Low 2021–2026

    50.7 °F

  • Average 2021–2026

    60.2 °F

  • Average High 2021–2026

    69.7 °F
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