Illiopolis Weather Forecast

    • 49
    • 76

    Rain Showers

    • 40
    • 61

    Chance Rain Showers

    • 46
    • 68

    Mostly Sunny

    • 37
    • 59

    Mostly Sunny

    • 42
    • 61

    Partly Sunny

    • 42
    • 66

    Slight Chance Rain Showers

Today 18 Oct Sangamon

A chance of Thunderstorms. A chance of Showers in the Morning, then Showers in the afternoon. Highs in the mid 70s. South Winds 10 to 15 Mph with Gusts up to 25 Mph. Chance of rain near 100 percent.

Tonight 18 Oct Sangamon

Partly cloudy. Near steady temperature in the mid 60s. South Winds around 10 Mph.

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Illiopolis Temperature Statistics

October Temperature

Decatur Airport (19.3 miles)

  • Lowest 9 October, 2025

    37.9 °F

  • Average October

    64.9 °F

  • Highest 3 October, 2025

    88 °F

Climate (2020–Present)

Decatur Airport (19.3 miles)

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  • Average Low 2020–2025

    45.3 °F

  • Average 2020–2025

    55.3 °F

  • Average High 2020–2025

    65.2 °F
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