Illiopolis, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Illiopolis, a village in Sangamon County, Illinois.
This Afternoon
73°F
Slight Chance T-storms
A slight chance of thunderstorms and a slight chance of rain before 1pm, then rain likely and a slight chance of thunderstorms. Mostly cloudy, with a high near 73. South wind 18 to 24 mph, with gusts as high as 37 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast for Illiopolis
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 73°F | Slight Chance T-storms | 18 to 24 mph S | 70% |
| Tonight | 54°F | Rain | 14 to 18 mph S | 80% |
| Wednesday | 60°F | Slight Chance Light Rain then Mostly Cloudy | 13 to 16 mph SW | 17% |
| Wednesday Night | 44°F | Mostly Cloudy | 10 mph SW | 1% |
| Thursday | 61°F | Mostly Sunny | 9 to 15 mph WSW | 4% |
| Thursday Night | 43°F | Mostly Cloudy then Slight Chance Light Rain | 3 to 8 mph NW | 22% |
| Friday | 55°F | Mostly Cloudy | 7 to 12 mph NNW | 13% |
| Friday Night | 36°F | Mostly Cloudy | 2 to 9 mph NNW | 6% |
| Saturday | 54°F | Mostly Sunny | 2 to 6 mph NW | 1% |
| Saturday Night | 34°F | Partly Cloudy | 3 mph W | 2% |
| Sunday | 60°F | Sunny | 2 to 9 mph W | 8% |
| Sunday Night | 34°F | Mostly Clear | 3 to 7 mph WNW | 5% |
| Monday | 64°F | Sunny | 3 to 12 mph SW | 3% |
| Monday Night | 39°F | Mostly Clear | 5 to 8 mph WSW | 2% |
Forecast source: National Weather Service (api.weather.gov) for Illiopolis (39.850, -89.252). Updated through the day.
Growing snapshot for Illiopolis
Last spring frost
Apr 14
First fall frost
Oct 24
Growing season
192 days
Hardiness zone
6a
More local growing data for Illiopolis: nearby ZIP 62539 weather · frost dates · planting calendar · Illinois frost dates
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Climate data from the nearest NOAA station, Decatur Wtp, Il (16.1 mi from Illiopolis). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 3, 2026.