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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

WhenTempForecastWindPrecip
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

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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.