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

Hazardous Weather Conditions

Current conditions at

St. Louis Regional Airport (KALN)

Lat: 38.89°NLon: 90.03°WElev: 518ft.

Fair

57°F

14°C

Humidity 60%
Wind Speed SE 6 mph
Barometer 29.93 in
Dewpoint 43°F (6°C)
Visibility 10.00 mi
Last update 15 May 3:35 am CDT
Extended Forecast for

Alton IL

  • Overnight

    Overnight: A 30 percent chance of showers and thunderstorms, mainly after 5am. Mostly clear early, then becoming mostly cloudy, with a low around 56. Southeast wind around 10 mph, with gusts as high as 21 mph.

    Low: 56 °F

    Chance
    T-storms

  • Friday

    Friday: Showers and thunderstorms likely, mainly before 9am. Mostly cloudy, then gradually becoming sunny, with a high near 83. South wind 11 to 14 mph, with gusts as high as 22 mph. Chance of precipitation is 60%.

    High: 83 °F

    Showers
    Likely then
    Mostly Sunny

  • Friday Night

    Friday Night: A slight chance of showers between 3am and 4am, then a chance of showers and thunderstorms after 4am. Mostly cloudy, with a low around 65. South wind 8 to 10 mph. Chance of precipitation is 30%.

    Low: 65 °F

    Partly Cloudy
    then Chance
    T-storms

  • Saturday

    Saturday: Showers and thunderstorms likely, mainly before 3pm. Partly sunny, with a high near 83. Southwest wind 7 to 9 mph. Chance of precipitation is 60%.

    High: 83 °F

    Showers
    Likely then
    Chance
    T-storms

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 63. South wind around 8 mph.

    Low: 63 °F

    Partly Cloudy

  • Sunday

    Sunday: Sunny, with a high near 89.

    High: 89 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 68.

    Low: 68 °F

    Mostly Clear

  • Monday

    Monday: A 50 percent chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 89.

    High: 89 °F

    Mostly Sunny
    then Chance
    T-storms

  • Monday Night

    Monday Night: A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 69.

    Low: 69 °F

    Chance
    T-storms

Detailed Forecast

Overnight
A 30 percent chance of showers and thunderstorms, mainly after 5am. Mostly clear early, then becoming mostly cloudy, with a low around 56. Southeast wind around 10 mph, with gusts as high as 21 mph.
Friday
Showers and thunderstorms likely, mainly before 9am. Mostly cloudy, then gradually becoming sunny, with a high near 83. South wind 11 to 14 mph, with gusts as high as 22 mph. Chance of precipitation is 60%.
Friday Night
A slight chance of showers between 3am and 4am, then a chance of showers and thunderstorms after 4am. Mostly cloudy, with a low around 65. South wind 8 to 10 mph. Chance of precipitation is 30%.
Saturday
Showers and thunderstorms likely, mainly before 3pm. Partly sunny, with a high near 83. Southwest wind 7 to 9 mph. Chance of precipitation is 60%.
Saturday Night
Partly cloudy, with a low around 63. South wind around 8 mph.
Sunday
Sunny, with a high near 89.
Sunday Night
Mostly clear, with a low around 68.
Monday
A 50 percent chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 89.
Monday Night
A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 69.
Tuesday
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Partly sunny, with a high near 86. Chance of precipitation is 70%.
Tuesday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 59. Chance of precipitation is 60%.
Wednesday
A 20 percent chance of showers and thunderstorms. Partly sunny, with a high near 75.
Wednesday Night
A 20 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 54.
Thursday
A 20 percent chance of showers and thunderstorms. Partly sunny, with a high near 74.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Alton IL
 38.91°N 90.13°W (Elev. 499 ft)
Last Update:
1:26 am CDT May 15, 2026
Forecast Valid:
3am CDT May 15, 2026-6pm CDT May 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