Illiopolis, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Illiopolis, a village in Sangamon County, Illinois.
Overnight
70°F
Mostly Clear
Mostly clear, with a low around 70. South southeast wind around 7 mph.
7-day forecast for Illiopolis
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 70°F | Mostly Clear | 7 mph SSE | 5% |
| Saturday | 90°F | Mostly Cloudy | 8 mph SSW | 13% |
| Saturday Night | 69°F | Partly Cloudy then Slight Chance Showers And Thunderstorms | 6 mph SSW | 22% |
| Sunday | 83°F | Chance Showers And Thunderstorms | 3 to 12 mph N | 48% |
| Sunday Night | 61°F | Chance Showers And Thunderstorms | 12 to 15 mph NE | 64% |
| Monday | 70°F | Showers And Thunderstorms Likely | 16 mph NE | 70% |
| Monday Night | 55°F | Chance Rain Showers | 12 to 15 mph NE | 49% |
| Tuesday | 68°F | Slight Chance Rain Showers | 15 mph NE | 20% |
| Tuesday Night | 52°F | Slight Chance Rain Showers then Mostly Cloudy | 7 to 13 mph NNE | 16% |
| Wednesday | 70°F | Mostly Sunny | 12 mph NNE | 2% |
| Wednesday Night | 54°F | Partly Cloudy | 5 to 10 mph NNE | 2% |
| Thursday | 72°F | Mostly Sunny | 6 to 9 mph NNE | 2% |
| Thursday Night | 55°F | Partly Cloudy | 5 to 9 mph NNE | 2% |
| Friday | 75°F | Mostly Sunny | 5 to 10 mph NE | 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 Sep 19, 2026.