National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce
Current conditions at

St. Louis Regional Airport (KALN)

Lat: 38.89°NLon: 90.03°WElev: 518ft.

Fair

44°F

7°C

Humidity 68%
Wind Speed Calm
Barometer 30.31 in
Dewpoint 34°F (1°C)
Visibility 10.00 mi
Last update 6 Apr 12:15 am CDT
Extended Forecast for

Alton IL

  • Overnight

    Overnight: Clear, with a low around 39. West wind 3 to 5 mph.

    Low: 39 °F

    Clear

  • Monday

    Monday: Sunny, with a high near 62. Northwest wind 8 to 13 mph, with gusts as high as 21 mph.

    High: 62 °F

    Sunny

  • Monday Night

    Monday Night: A chance of rain showers after 1am, mixing with snow after 4am. Increasing clouds, with a low around 37. Northeast wind 8 to 11 mph, with gusts as high as 21 mph. Chance of precipitation is 30%.

    Low: 37 °F

    Partly Cloudy
    then Chance
    Rain/Snow

  • Tuesday

    Tuesday: Mostly cloudy, with a high near 52. East wind 9 to 11 mph.

    High: 52 °F

    Mostly Cloudy

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 40. Southeast wind around 8 mph.

    Low: 40 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 72.

    High: 72 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 55.

    Low: 55 °F

    Partly Cloudy

  • Thursday

    Thursday: A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 72. Chance of precipitation is 30%.

    High: 72 °F

    Chance
    Showers

  • Thursday Night

    Thursday Night: A 30 percent chance of showers and thunderstorms, mainly after 1am. Mostly cloudy, with a low around 56.

    Low: 56 °F

    Slight Chance
    T-storms then
    Chance
    Showers

Detailed Forecast

Overnight
Clear, with a low around 39. West wind 3 to 5 mph.
Monday
Sunny, with a high near 62. Northwest wind 8 to 13 mph, with gusts as high as 21 mph.
Monday Night
A chance of rain showers after 1am, mixing with snow after 4am. Increasing clouds, with a low around 37. Northeast wind 8 to 11 mph, with gusts as high as 21 mph. Chance of precipitation is 30%.
Tuesday
Mostly cloudy, with a high near 52. East wind 9 to 11 mph.
Tuesday Night
Mostly cloudy, with a low around 40. Southeast wind around 8 mph.
Wednesday
Mostly sunny, with a high near 72.
Wednesday Night
Partly cloudy, with a low around 55.
Thursday
A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 72. Chance of precipitation is 30%.
Thursday Night
A 30 percent chance of showers and thunderstorms, mainly after 1am. Mostly cloudy, with a low around 56.
Friday
A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 74.
Friday Night
A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 55.
Saturday
A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 79.
Saturday Night
A 30 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 61.
Sunday
A 50 percent chance of showers and thunderstorms. Partly sunny, with a high near 81.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Alton IL
 38.91°N 90.16°W (Elev. 505 ft)
Last Update:
12:21 am CDT Apr 6, 2026
Forecast Valid:
12am CDT Apr 6, 2026-6pm CDT Apr 12, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation