Illinois City, IL Weather & Growing Conditions
Tonight
69°F
Mostly Cloudy then Chance Showers And Thunderstorms
A chance of showers and thunderstorms between 2am and 4am, then showers and thunderstorms likely. Mostly cloudy. Low around 69, with temperatures rising to around 71 overnight. Southeast wind 5 to 10 mph, with gusts as high as 20 mph. Chance of precipitation is 60%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 69°F | Mostly Cloudy then Chance Showers And Thunderstorms | 5 to 10 mph SE | 56% |
| Saturday | 84°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 to 10 mph S | 62% |
| Saturday Night | 65°F | Chance Showers And Thunderstorms then Showers And Thunderstorms | 5 mph N | 81% |
| Sunday | 72°F | Showers And Thunderstorms Likely | 5 to 15 mph NE | 78% |
| Sunday Night | 58°F | Showers And Thunderstorms Likely | 10 to 15 mph NE | 63% |
| Monday | 65°F | Rain Showers Likely | 15 mph NE | 57% |
| Monday Night | 54°F | Rain Showers Likely | 10 to 15 mph NE | 56% |
| Tuesday | 64°F | Chance Showers And Thunderstorms | 10 to 15 mph NE | 41% |
| Tuesday Night | 50°F | Partly Cloudy | 5 to 10 mph NE | 6% |
| Wednesday | 68°F | Mostly Sunny | 5 mph NE | 1% |
| Wednesday Night | 53°F | Partly Cloudy | 0 to 5 mph NE | 2% |
| Thursday | 70°F | Mostly Sunny | 5 mph NE | 5% |
| Thursday Night | 55°F | Partly Cloudy | 0 to 5 mph NE | 6% |
| Friday | 72°F | Mostly Sunny | 0 to 5 mph NE | 6% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Illinois City, IL
Last spring frost
Apr 18
First fall frost
Oct 24
Growing season
188 days
Hardiness zone
5b
Explore more for Illinois City, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Illinois City Dam 16, Il (5.2 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.