Illiopolis Weather Forecast
- 55
- 78
Slight Chance Thunderstorms
- 56
- 79
Severe Tstms
- 34
- 67
Slight Chance Rain Showers
- 34
- 48
Mostly Sunny
- 49
- 65
Mostly Sunny
- 52
- 73
Mostly Cloudy
- 34
- 67
Rain Likely
Today 13 Mar Sangamon
Sunny. Near steady temperature in the mid 70s. Southeast Winds 5 to 10 Mph.
Tonight 13 Mar Sangamon
Mostly clear with a slight chance of Showers and Thunderstorms in the Evening, then partly cloudy after midnight. Not as cool with Lows in the mid 50s. Southeast Winds 5 to 10 Mph with Gusts up to 20 Mph. Chance of rain 20 percent.
Illiopolis Temperature Statistics
March Temperature
Decatur Airport (19.3 miles)
Lowest 2 March, 2025
16.8 °FAverage March
44.3 °FHighest 11 March, 2025
73.9 °F
Climate (2020–Present)
Decatur Airport (19.3 miles)
Average Low 2020–2025
44.9 °FAverage 2020–2025
54.8 °FAverage High 2020–2025
64.5 °F