Alton, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Alton, a city in Madison County, Illinois.
This Afternoon
98°F
Mostly Cloudy
Mostly cloudy, with a high near 98. Heat index values as high as 100. Southwest wind around 7 mph.
7-day forecast for Alton
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 98°F | Mostly Cloudy | 7 mph SW | 1% |
| Tonight | 73°F | Partly Cloudy | 5 mph S | 1% |
| Sunday | 93°F | Partly Sunny then Chance Showers And Thunderstorms | 3 to 8 mph W | 31% |
| Sunday Night | 66°F | Chance Showers And Thunderstorms | 6 to 10 mph NE | 73% |
| Monday | 80°F | Showers And Thunderstorms Likely | 7 to 10 mph NE | 73% |
| Monday Night | 60°F | Chance Showers And Thunderstorms | 6 to 10 mph NE | 49% |
| Tuesday | 73°F | Chance Rain Showers then Mostly Cloudy | 8 to 13 mph N | 25% |
| Tuesday Night | 55°F | Mostly Cloudy | 6 to 13 mph N | 2% |
| Wednesday | 74°F | Partly Sunny | 10 mph N | 0% |
| Wednesday Night | 55°F | Partly Cloudy | 2 to 9 mph N | 0% |
| Thursday | 77°F | Mostly Sunny | 3 to 7 mph N | 1% |
| Thursday Night | 59°F | Mostly Cloudy then Slight Chance Rain Showers | 2 to 6 mph NE | 15% |
| Friday | 80°F | Slight Chance Rain Showers | 3 to 7 mph NE | 18% |
| Friday Night | 59°F | Slight Chance Rain Showers then Partly Cloudy | 3 to 7 mph NE | 18% |
Forecast source: National Weather Service (api.weather.gov) for Alton (38.904, -90.151). Updated through the day.
Growing snapshot for Alton
Last spring frost
Apr 4
First fall frost
Nov 5
Growing season
214 days
Hardiness zone
7a
More local growing data for Alton: nearby ZIP 62002 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Alhambra
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
Williamson
Wood River
Climate data from the nearest NOAA station, Alton - Melvin Price L&D, Il (5.1 mi from Alton). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.