Belleville, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Belleville, a city in St. Clair County, Illinois.
Tonight
73°F
Slight Chance Showers And Thunderstorms then Mostly Clear
A slight chance of showers and thunderstorms before 10pm. Mostly clear, with a low around 73. Heat index values as high as 102. Southeast wind around 3 mph. Chance of precipitation is 20%.
7-day forecast for Belleville
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 73°F | Slight Chance Showers And Thunderstorms then Mostly Clear | 3 mph SE | 24% |
| Saturday | 99°F | Mostly Sunny | 3 to 7 mph SW | 6% |
| Saturday Night | 74°F | Partly Cloudy | 5 mph S | 1% |
| Sunday | 95°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 3 to 7 mph W | 17% |
| Sunday Night | 68°F | Slight Chance Showers And Thunderstorms then Chance Showers And Thunderstorms | 7 mph N | 54% |
| Monday | 82°F | Showers And Thunderstorms Likely | 6 to 10 mph N | 67% |
| Monday Night | 62°F | Showers And Thunderstorms Likely | 7 to 12 mph N | 67% |
| Tuesday | 73°F | Chance Rain Showers then Mostly Cloudy | 12 mph N | 27% |
| Tuesday Night | 56°F | Mostly Cloudy | 5 to 12 mph N | 6% |
| Wednesday | 75°F | Mostly Sunny | 6 to 9 mph N | 3% |
| Wednesday Night | 56°F | Partly Cloudy | 3 to 8 mph N | 2% |
| Thursday | 77°F | Mostly Sunny | 3 to 8 mph N | 2% |
| Thursday Night | 58°F | Partly Cloudy | 3 to 7 mph N | 2% |
| Friday | 77°F | Mostly Sunny | 3 to 8 mph N | 5% |
Forecast source: National Weather Service (api.weather.gov) for Belleville (38.516, -89.990). Updated through the day.
Growing snapshot for Belleville
Last spring frost
Apr 12
First fall frost
Oct 20
Growing season
189 days
Hardiness zone
7a
More local growing data for Belleville: nearby ZIP 62226 weather · frost dates · planting calendar · Illinois frost dates
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Climate data from the nearest NOAA station, Belleville Siu Rsch, Il (8.4 mi from Belleville). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.