Mascoutah Weather Forecast

    • 63
    • 83

    Isolated Thunderstorms

    • 64
    • 82

    Chance Thunderstorms

    • 63
    • 85

    Chance Rain Showers

    • 59
    • 82

    Mostly Sunny

    • 60
    • 81

    Mostly Sunny

    • 65
    • 84

    Partly Sunny

Today 30 May St. Clair

Mostly sunny. Isolated Showers and Thunderstorms. Highs in the lower 80s. East Winds 5 to 10 Mph. Chance of rain 20 percent.

Tonight 30 May St. Clair

Mostly cloudy. Lows in the mid 60s. East Winds 5 to 10 Mph.

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Mascoutah Temperature Statistics

May Temperature

Belleville, Scott AFB/MidAmerica Airport (5 miles)

  • Lowest 7 May, 2026

    40.1 °F

  • Average May

    65.7 °F

  • Highest 28 May, 2026

    86.7 °F

Climate (2021–Present)

Belleville, Scott AFB/MidAmerica Airport (5 miles)

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  • Average Low 2021–2026

    47.8 °F

  • Average 2021–2026

    57.8 °F

  • Average High 2021–2026

    68.1 °F
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