Illiopolis Weather Forecast

    • 62
    • 82

    Increasing Clouds

    • 68
    • 84

    Rain Showers Likely

    • 63
    • 81

    Rain Showers Likely

    • 60
    • 79

    Partly Sunny

    • 62
    • 81

    Mostly Sunny

    • 62
    • 81

    Mostly Sunny

Today 17 Aug Sangamon

Mostly sunny. Highs in the lower 80s. North Winds 5 to 10 Mph.

Tonight 17 Aug Sangamon

Mostly cloudy with a chance of Showers and Thunderstorms. Lows in the upper 60s. Northwest Winds around 5 Mph. Chance of rain 50 percent.

Graph Plots Open in Graphs

  • Temperature Forecast NOAA

  • Temperature Real-Time

Illiopolis Temperature Statistics

August Temperature

Decatur Airport (19.3 miles)

  • Lowest 4 August, 2026

    60.7 °F

  • Average August

    76.7 °F

  • Highest 11 August, 2026

    92.6 °F

Climate (2021–2026)

Decatur Airport (19.3 miles)

Take a look at our website widgetsAvailable free! Find Out More

  • Average Low 2021–2026

    45.4 °F

  • Average 2021–2026

    55.5 °F

  • Average High 2021–2026

    65.6 °F
Get WillyWeather+ to remove ads