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.

A Few Clouds

93°F

34°C

Humidity 47%
Wind Speed SW 16 mph
Barometer 29.91 in
Dewpoint 70°F (21°C)
Visibility 10.00 mi
Heat Index99°F (37°C)
Last update 21 Jun 5:50 pm CDT
Extended Forecast for

Alton IL

Extreme Heat Warning June 21, 05:56pm until June 24, 09:00pm
Click here for hazard details and duration
Extreme Heat Warning
  •  
    Extreme Heat Warning June 21, 05:56pm until June 24, 09:00pm

    NOW until 9:00pm Tue

    Extreme Heat Warning

  • Tonight

    Low: 77 °F

    Clear

  • Sunday

    Sunday: Sunny and hot, with a high near 97. Heat index values as high as 104. Southwest wind 8 to 13 mph, with gusts as high as 20 mph.

    High: 97 °F

    Hot

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 76. South wind 6 to 10 mph.

    Low: 76 °F

    Mostly Clear

  • Monday

    Monday: Sunny and hot, with a high near 97. Heat index values as high as 102. Southwest wind 6 to 8 mph.

    High: 97 °F

    Hot

  • Monday Night

    Monday Night: Partly cloudy, with a low around 76. South wind 3 to 8 mph.

    Low: 76 °F

    Partly Cloudy

  • Tuesday

    Tuesday: A 20 percent chance of showers and thunderstorms before 1pm. Mostly sunny, with a high near 95.

    High: 95 °F

    Slight Chance
    T-storms

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 75.

    Low: 75 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 93.

    High: 93 °F

    Mostly Sunny

Detailed Forecast

Tonight
Clear, with a low around 77. South wind 6 to 11 mph, with gusts as high as 24 mph.
Sunday
Sunny and hot, with a high near 97. Heat index values as high as 104. Southwest wind 8 to 13 mph, with gusts as high as 20 mph.
Sunday Night
Mostly clear, with a low around 76. South wind 6 to 10 mph.
Monday
Sunny and hot, with a high near 97. Heat index values as high as 102. Southwest wind 6 to 8 mph.
Monday Night
Partly cloudy, with a low around 76. South wind 3 to 8 mph.
Tuesday
A 20 percent chance of showers and thunderstorms before 1pm. Mostly sunny, with a high near 95.
Tuesday Night
Partly cloudy, with a low around 75.
Wednesday
Mostly sunny, with a high near 93.
Wednesday Night
Partly cloudy, with a low around 75.
Thursday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 94.
Thursday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 74.
Friday
A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 92.
Friday Night
A 20 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 74.
Saturday
A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 91.
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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:
5:52 pm CDT Jun 21, 2025
Forecast Valid:
5pm CDT Jun 21, 2025-6pm CDT Jun 28, 2025
 
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