Williamson, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Williamson, a village in Madison County, Illinois.
Tonight
70°F
Slight Chance Showers And Thunderstorms then Mostly Clear
A slight chance of showers and thunderstorms before 10pm. Mostly clear, with a low around 70. Southeast wind around 6 mph. Chance of precipitation is 20%.
7-day forecast for Williamson
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 70°F | Slight Chance Showers And Thunderstorms then Mostly Clear | 6 mph SE | 21% |
| Saturday | 96°F | Mostly Sunny | 3 to 8 mph SW | 6% |
| Saturday Night | 70°F | Mostly Cloudy | 5 mph S | 4% |
| Sunday | 92°F | Chance Rain Showers then Chance Showers And Thunderstorms | 2 to 7 mph NW | 25% |
| Sunday Night | 64°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 8 mph N | 58% |
| Monday | 78°F | Rain Showers Likely | 6 to 12 mph NE | 65% |
| Monday Night | 57°F | Showers And Thunderstorms Likely | 7 to 13 mph NE | 65% |
| Tuesday | 71°F | Slight Chance Rain Showers then Mostly Cloudy | 12 mph N | 24% |
| Tuesday Night | 52°F | Mostly Cloudy | 5 to 12 mph N | 5% |
| Wednesday | 74°F | Mostly Sunny | 6 to 9 mph N | 3% |
| Wednesday Night | 53°F | Partly Cloudy | 2 to 8 mph N | 2% |
| Thursday | 76°F | Mostly Sunny | 3 to 8 mph N | 3% |
| Thursday Night | 56°F | Partly Cloudy | 2 to 7 mph NE | 3% |
| Friday | 76°F | Mostly Sunny | 3 to 7 mph NE | 4% |
Forecast source: National Weather Service (api.weather.gov) for Williamson (38.985, -89.763). Updated through the day.
Growing snapshot for Williamson
Last spring frost
Apr 13
First fall frost
Oct 24
Growing season
192 days
Hardiness zone
6b
More local growing data for Williamson: nearby ZIP 62058 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Alhambra
Alton
Bethalto
Collinsville
East Alton
Edwardsville
Glen Carbon
Godfrey
Granite City
Grantfork
Hamel
Hartford
Highland
Holiday Shores
Livingston
Madison
Marine
Maryville
Mitchell
Moro
New Douglas
Pontoon Beach
Prairietown
Rosewood Heights
Roxana
South Roxana
St. Jacob
Troy
Venice
Wood River
Climate data from the nearest NOAA station, Hillsboro, Il (19.8 mi from Williamson). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.