Illiopolis, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Illiopolis, a village in Sangamon County, Illinois.
Today
86°F
Sunny
Sunny, with a high near 86. South wind around 6 mph.
7-day forecast for Illiopolis
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 86°F | Sunny | 6 mph S | 0% |
| Tonight | 67°F | Mostly Clear | 5 mph SSE | 0% |
| Wednesday | 87°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 5 to 8 mph S | 15% |
| Wednesday Night | 68°F | Chance Showers And Thunderstorms | 3 to 7 mph S | 80% |
| Thursday | 82°F | Showers And Thunderstorms | 7 mph SSW | 80% |
| Thursday Night | 66°F | Slight Chance Showers And Thunderstorms | 2 to 6 mph S | 21% |
| Friday | 84°F | Partly Sunny | 5 mph SW | 9% |
| Friday Night | 67°F | Slight Chance Showers And Thunderstorms | 3 mph SSW | 21% |
| Saturday | 86°F | Slight Chance Showers And Thunderstorms then Mostly Sunny | 3 to 7 mph SSW | 19% |
| Saturday Night | 70°F | Mostly Clear | 5 to 8 mph S | 11% |
| Sunday | 88°F | Sunny | 8 to 13 mph SSW | 5% |
| Sunday Night | 73°F | Mostly Clear | 12 mph SSW | 11% |
| Monday | 89°F | Mostly Sunny | 12 mph SSW | 13% |
| Monday Night | 73°F | Slight Chance Showers And Thunderstorms | 10 mph SSW | 24% |
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 Aug 4, 2026.