Collinsville, IL Weather & Growing Conditions
Today
87°F
Sunny
Sunny, with a high near 87. South wind 2 to 6 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 87°F | Sunny | 2 to 6 mph S | 0% |
| Tonight | 68°F | Mostly Clear | 2 to 6 mph SE | 0% |
| Wednesday | 91°F | Sunny | 2 to 6 mph S | 8% |
| Wednesday Night | 72°F | Slight Chance Showers And Thunderstorms | 7 mph S | 67% |
| Thursday | 87°F | Showers And Thunderstorms Likely | 6 mph S | 72% |
| Thursday Night | 71°F | Chance Showers And Thunderstorms | 5 mph SE | 42% |
| Friday | 87°F | Chance Showers And Thunderstorms | 5 mph SW | 42% |
| Friday Night | 71°F | Chance Showers And Thunderstorms | 5 mph S | 35% |
| Saturday | 89°F | Chance Showers And Thunderstorms then Mostly Sunny | 5 mph S | 35% |
| Saturday Night | 73°F | Mostly Clear | 7 mph S | 8% |
| Sunday | 92°F | Sunny | 5 to 9 mph S | 7% |
| Sunday Night | 75°F | Mostly Clear | 6 to 9 mph S | 5% |
| Monday | 93°F | Sunny | 6 to 9 mph S | 5% |
| Monday Night | 76°F | Slight Chance Showers And Thunderstorms | 9 mph S | 15% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Collinsville, IL
Last spring frost
Apr 8
First fall frost
Oct 26
Growing season
200 days
Hardiness zone
7a
Explore more for Collinsville, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Cahokia St Louis Ap, Il (12.2 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.