Illiopolis Weather Forecast

    • 36
    • 50

    Increasing Clouds

    • 20
    • 42

    Chance Rain

    • 23
    • 32

    Mostly Sunny

    • 33
    • 44

    Partly Sunny

    • 33
    • 49

    Chance Rain

    • 21
    • 38

    Mostly Cloudy

Today 9 Jan Sangamon

Mostly cloudy in the Morning, then becoming partly sunny. Cooler with Highs around 50. Northwest Winds 15 to 20 Mph with Gusts up to 30 Mph, Diminishing to 5 to 10 Mph in the afternoon.

Tonight 9 Jan Sangamon

Mostly cloudy. Lows in the mid 30s. North Winds around 5 Mph.

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Illiopolis Temperature Statistics

January Temperature

Decatur Airport (19.3 miles)

  • Lowest 1 January, 2026

    19 °F

  • Average January

    34.1 °F

  • Highest 5 January, 2026

    52 °F

Climate (2021–Present)

Decatur Airport (19.3 miles)

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  • Average Low 2021–2026

    45.3 °F

  • Average 2021–2026

    55.3 °F

  • Average High 2021–2026

    65.2 °F
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