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.

Partly Cloudy

75°F

24°C

Humidity 78%
Wind Speed W 7 mph
Barometer 30.05 in
Dewpoint 68°F (20°C)
Visibility 10.00 mi
Last update 14 Oct 4:50 pm CDT
Extended Forecast for

Alton IL

  • This Afternoon

    This Afternoon: A 20 percent chance of rain. Mostly cloudy, with a high near 77. Northwest wind around 5 mph.

    High: 77 °F

    Slight Chance
    Rain

  • Tonight

    Tonight: A slight chance of rain, then a chance of showers and thunderstorms after 2am. Mostly cloudy, with a low around 66. Calm wind becoming east around 5 mph after midnight. Chance of precipitation is 30%.

    Low: 66 °F

    Slight Chance
    Rain then
    Chance
    T-storms

  • Thursday

    Thursday: Showers and possibly a thunderstorm, mainly before noon, then a chance of showers and thunderstorms after noon. High near 82. East wind 5 to 10 mph becoming southwest in the afternoon. Chance of precipitation is 90%.

    High: 82 °F

    Showers then
    Chance
    T-storms

  • Thursday Night

    Thursday Night: A chance of showers and thunderstorms before 3am, then a slight chance of showers between 3am and 4am. Mostly cloudy, with a low around 49. Northwest wind 9 to 17 mph, with gusts as high as 25 mph. Chance of precipitation is 50%.

    Low: 49 °F

    Chance
    Showers

  • Friday

    Friday: A 20 percent chance of showers after 1pm. Mostly cloudy, with a high near 56. Breezy, with a northwest wind 18 to 21 mph, with gusts as high as 31 mph.

    High: 56 °F

    Breezy.
    Mostly Cloudy
    then Slight
    Chance
    Showers

  • Friday Night

    Friday Night: Partly cloudy, with a low around 40.

    Low: 40 °F

    Partly Cloudy

  • Saturday

    Saturday: Sunny, with a high near 62.

    High: 62 °F

    Sunny

  • Saturday Night

    Saturday Night: Clear, with a low around 38.

    Low: 38 °F

    Clear

  • Sunday

    Sunday: Sunny, with a high near 67.

    High: 67 °F

    Sunny

Detailed Forecast

This Afternoon
A 20 percent chance of rain. Mostly cloudy, with a high near 77. Northwest wind around 5 mph.
Tonight
A slight chance of rain, then a chance of showers and thunderstorms after 2am. Mostly cloudy, with a low around 66. Calm wind becoming east around 5 mph after midnight. Chance of precipitation is 30%.
Thursday
Showers and possibly a thunderstorm, mainly before noon, then a chance of showers and thunderstorms after noon. High near 82. East wind 5 to 10 mph becoming southwest in the afternoon. Chance of precipitation is 90%.
Thursday Night
A chance of showers and thunderstorms before 3am, then a slight chance of showers between 3am and 4am. Mostly cloudy, with a low around 49. Northwest wind 9 to 17 mph, with gusts as high as 25 mph. Chance of precipitation is 50%.
Friday
A 20 percent chance of showers after 1pm. Mostly cloudy, with a high near 56. Breezy, with a northwest wind 18 to 21 mph, with gusts as high as 31 mph.
Friday Night
Partly cloudy, with a low around 40.
Saturday
Sunny, with a high near 62.
Saturday Night
Clear, with a low around 38.
Sunday
Sunny, with a high near 67.
Sunday Night
Mostly clear, with a low around 42.
Monday
Mostly sunny, with a high near 73.
Monday Night
Partly cloudy, with a low around 45.
Tuesday
Mostly sunny, with a high near 76.
Tuesday Night
Mostly clear, with a low around 51.
Wednesday
Sunny, with a high near 80.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Alton IL
 38.91°N 90.16°W (Elev. 505 ft)
Last Update:
4:46 pm CDT Oct 14, 2026
Forecast Valid:
5pm CDT Oct 14, 2026-6pm CDT Oct 21, 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