Collinsville, IL Weather & Growing Conditions
This Afternoon
97°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms. Sunny, with a high near 97. Heat index values as high as 104. South wind around 5 mph. Chance of precipitation is 30%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 97°F | Chance Showers And Thunderstorms | 5 mph S | 26% |
| Tonight | 74°F | Slight Chance Showers And Thunderstorms then Mostly Clear | 6 mph SE | 24% |
| Saturday | 98°F | Mostly Sunny | 5 to 8 mph SW | 6% |
| Saturday Night | 74°F | Partly Cloudy | 6 mph S | 1% |
| Sunday | 94°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 3 to 8 mph W | 19% |
| Sunday Night | 68°F | Slight Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 8 mph N | 58% |
| Monday | 81°F | Rain Showers Likely | 6 to 12 mph N | 68% |
| Monday Night | 61°F | Showers And Thunderstorms Likely | 8 to 13 mph N | 68% |
| Tuesday | 72°F | Chance Rain Showers then Mostly Cloudy | 13 mph N | 28% |
| Tuesday Night | 55°F | Mostly Cloudy | 6 to 13 mph N | 6% |
| Wednesday | 75°F | Mostly Sunny | 7 to 10 mph N | 3% |
| Wednesday Night | 56°F | Partly Cloudy | 3 to 9 mph N | 2% |
| Thursday | 76°F | Mostly Sunny | 3 to 9 mph N | 3% |
| Thursday Night | 59°F | Partly Cloudy | 3 to 8 mph N | 3% |
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 Sep 19, 2026.