Granite City, IL Weather & Growing Conditions
Tonight
74°F
Slight Chance Showers And Thunderstorms then Mostly Clear
A slight chance of showers and thunderstorms before 10pm. Mostly clear, with a low around 74. Heat index values as high as 102. Southeast wind around 5 mph. Chance of precipitation is 20%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 74°F | Slight Chance Showers And Thunderstorms then Mostly Clear | 5 mph SE | 24% |
| Saturday | 99°F | Mostly Sunny | 3 to 8 mph SW | 6% |
| Saturday Night | 74°F | Partly Cloudy | 5 mph S | 2% |
| Sunday | 94°F | Slight Chance Rain Showers then Slight Chance Showers And Thunderstorms | 3 to 7 mph W | 20% |
| Sunday Night | 68°F | Slight Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 to 8 mph N | 60% |
| Monday | 81°F | Rain Showers Likely | 5 to 10 mph N | 70% |
| Monday Night | 61°F | Showers And Thunderstorms Likely | 7 to 12 mph N | 70% |
| Tuesday | 73°F | Chance Rain Showers then Mostly Cloudy | 9 to 13 mph N | 27% |
| Tuesday Night | 55°F | Mostly Cloudy | 5 to 13 mph N | 6% |
| Wednesday | 76°F | Mostly Sunny | 9 mph N | 2% |
| Wednesday Night | 56°F | Partly Cloudy | 3 to 8 mph N | 2% |
| Thursday | 77°F | Mostly Sunny | 3 to 8 mph N | 3% |
| Thursday Night | 58°F | Partly Cloudy | 3 to 7 mph N | 3% |
| Friday | 77°F | Mostly Sunny | 3 to 8 mph N | 6% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Granite City, IL
Last spring frost
Apr 8
First fall frost
Oct 26
Growing season
200 days
Hardiness zone
7a
Explore more for Granite City, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Cahokia St Louis Ap, Il (10.4 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.