Illiopolis Weather Forecast

    • 49
    • 77

    Decreasing Clouds

    • 51
    • 74

    Mostly Cloudy

    • 54
    • 76

    Mostly Sunny

    • 56
    • 81

    Slight Chance Thunderstorms

    • 56
    • 79

    Mostly Cloudy

    • 55
    • 75

    Chance Rain Showers

Today 26 Oct Sangamon

Mostly sunny. Highs in the upper 70s. South Winds around 5 Mph.

Tonight 26 Oct Sangamon

Mostly clear in the Evening, then becoming mostly cloudy. Lows in the upper 40s. Southeast Winds around 5 Mph.

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Illiopolis Temperature Statistics

October Temperature

Decatur Airport (19.3 miles)

  • Lowest 18 October, 2026

    32.6 °F

  • Average October

    61.7 °F

  • Highest 13 October, 2026

    90.6 °F

Climate (2021–2026)

Decatur Airport (19.3 miles)

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  • Average Low 2021–2026

    45.3 °F

  • Average 2021–2026

    55.6 °F

  • Average High 2021–2026

    65.7 °F
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