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

Dangerous Heat over the South-Central and Southwest U.S. Through Next Week

Dangerous heat persists across the Desert Southwest through this weekend and across the Southern Plains and Lower Mississippi Valley through at least the middle of next week. Numerous daily record high temperatures are expected through at least Tuesday for much of Texas and Oklahoma as well as portions of Louisiana, New Mexico, and Arizona. Read More >

Current conditions at

St. Louis Regional Airport (KALN)

Lat: 38.89°NLon: 90.03°WElev: 518ft.

Fair

65°F

18°C

Humidity 94%
Wind Speed NW 3 mph
Barometer 30.07 in
Dewpoint 63°F (17°C)
Visibility 10.00 mi
Last update 23 Aug 2:15 am CDT
Extended Forecast for

Alton IL

  • Overnight

    Overnight: Clear, with a low around 63. Light northwest wind.

    Low: 63 °F

    Clear

  • Sunday

    Sunday: Sunny, with a high near 82. Light northwest wind increasing to 5 to 9 mph in the morning.

    High: 82 °F

    Sunny

  • Sunday Night

    Sunday Night: Increasing clouds, with a low around 60. North wind around 6 mph becoming calm in the evening.

    Low: 60 °F

    Increasing
    Clouds

  • Monday

    Monday: Mostly sunny, with a high near 82. East wind 3 to 5 mph.

    High: 82 °F

    Mostly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 63. East wind around 5 mph becoming calm in the evening.

    Low: 63 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 84.

    High: 84 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 67.

    Low: 67 °F

    Partly Cloudy

  • Wednesday

    Wednesday: A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 88.

    High: 88 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A 20 percent chance of showers and thunderstorms before 1am. Mostly clear, with a low around 68.

    Low: 68 °F

    Slight Chance
    T-storms

Detailed Forecast

Overnight
Clear, with a low around 63. Light northwest wind.
Sunday
Sunny, with a high near 82. Light northwest wind increasing to 5 to 9 mph in the morning.
Sunday Night
Increasing clouds, with a low around 60. North wind around 6 mph becoming calm in the evening.
Monday
Mostly sunny, with a high near 82. East wind 3 to 5 mph.
Monday Night
Partly cloudy, with a low around 63. East wind around 5 mph becoming calm in the evening.
Tuesday
Mostly sunny, with a high near 84.
Tuesday Night
Partly cloudy, with a low around 67.
Wednesday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 88.
Wednesday Night
A 20 percent chance of showers and thunderstorms before 1am. Mostly clear, with a low around 68.
Thursday
Sunny, with a high near 87.
Thursday Night
Mostly clear, with a low around 65.
Friday
Sunny, with a high near 85.
Friday Night
Partly cloudy, with a low around 66.
Saturday
A 20 percent chance of showers. Mostly sunny, with a high near 86.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Alton IL
 38.93°N 90.16°W (Elev. 505 ft)
Last Update:
1:26 am CDT Aug 23, 2026
Forecast Valid:
2am CDT Aug 23, 2026-6pm CDT Aug 29, 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