Alton Weather Forecast

    • 64
    • 87

    Mostly Sunny

    • 65
    • 84

    Mostly Sunny

    • 66
    • 87

    Mostly Sunny

    • 61
    • 86

    Mostly Sunny

    • 57
    • 80

    Mostly Sunny

    • 55
    • 76

    Partly Sunny

    • 55
    • 76

    Partly Sunny

Today 20 Aug Madison

Mostly sunny. Highs in the upper 80s. Northeast Winds 5 to 10 Mph.

Tonight 20 Aug Madison

Mostly clear. Lows in the mid 60s. Northeast Winds 5 to 10 Mph.

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Alton Temperature Statistics

August Temperature

St. Louis Regional Airport (8.1 miles)

  • Lowest 3 August, 2025

    56.7 °F

  • Average August

    74.6 °F

  • Highest 16 August, 2025

    95 °F

Climate (2020–Present)

St. Louis Regional Airport (8.1 miles)

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  • Average Low 2020–2025

    46.1 °F

  • Average 2020–2025

    53.9 °F

  • Average High 2020–2025

    66 °F
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