Illiopolis, IL Weather & Growing Conditions
This Afternoon
73°F
Light Rain Likely
Rain likely and a slight chance of thunderstorms. Mostly cloudy, with a high near 73. South southeast wind 20 to 24 mph, with gusts as high as 36 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 73°F | Light Rain Likely | 20 to 24 mph SSE | 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 | 45°F | Mostly Cloudy | 8 to 12 mph SW | 1% |
| Thursday | 61°F | Mostly Sunny | 10 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 10 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 10 mph W | 9% |
| 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). Updated through the day.
Growing snapshot for Illiopolis, IL
Last spring frost
Apr 14
First fall frost
Oct 24
Growing season
192 days
Hardiness zone
6a
Explore more for Illiopolis, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Decatur Wtp, Il (16.1 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 3, 2026.