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.

Fog/Mist

75°F

24°C

Humidity 95%
Wind Speed SW 3 mph
Barometer 30.01 in
Dewpoint 74°F (23°C)
Visibility 5.00 mi
Last update 18 Aug 3:35 am CDT
Extended Forecast for

Glen Carbon IL

Heat Advisory August 18, 03:49am until August 18, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 18, 03:49am until August 18, 08:00pm

    NOW until 8:00pm Mon

    Heat Advisory

  • Overnight

    Low: 78 °F

    Partly Cloudy

  • Monday

    Monday: Mostly sunny, with a high near 94. Heat index values as high as 107. South wind 3 to 7 mph.

    High: 94 °F

    Mostly Sunny

  • Monday Night

    Monday Night: A 20 percent chance of showers and thunderstorms after 4am. Partly cloudy, with a low around 73. South wind 3 to 5 mph.

    Low: 73 °F

    Partly Cloudy
    then Slight
    Chance
    T-storms

  • Tuesday

    Tuesday: A 40 percent chance of showers and thunderstorms, mainly after 7am. Mostly sunny, with a high near 93. Heat index values as high as 103. Calm wind becoming west around 6 mph in the morning.

    High: 93 °F

    Chance
    Showers then
    Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 74. North wind around 5 mph becoming calm in the evening.

    Low: 74 °F

    Chance
    T-storms

  • Wednesday

    Wednesday: A slight chance of showers, then a chance of showers and thunderstorms after 10am. Mostly sunny, with a high near 88. Chance of precipitation is 30%.

    High: 88 °F

    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A chance of thunderstorms before 7pm. Partly cloudy, with a low around 66. Chance of precipitation is 30%.

    Low: 66 °F

    Chance
    T-storms then
    Partly Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 86.

    High: 86 °F

    Mostly Sunny

Detailed Forecast

Overnight
Partly cloudy, with a low around 78. Calm wind.
Monday
Mostly sunny, with a high near 94. Heat index values as high as 107. South wind 3 to 7 mph.
Monday Night
A 20 percent chance of showers and thunderstorms after 4am. Partly cloudy, with a low around 73. South wind 3 to 5 mph.
Tuesday
A 40 percent chance of showers and thunderstorms, mainly after 7am. Mostly sunny, with a high near 93. Heat index values as high as 103. Calm wind becoming west around 6 mph in the morning.
Tuesday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 74. North wind around 5 mph becoming calm in the evening.
Wednesday
A slight chance of showers, then a chance of showers and thunderstorms after 10am. Mostly sunny, with a high near 88. Chance of precipitation is 30%.
Wednesday Night
A chance of thunderstorms before 7pm. Partly cloudy, with a low around 66. Chance of precipitation is 30%.
Thursday
Mostly sunny, with a high near 86.
Thursday Night
Mostly clear, with a low around 65.
Friday
Sunny, with a high near 87.
Friday Night
Mostly clear, with a low around 66.
Saturday
Mostly sunny, with a high near 87.
Saturday Night
Mostly clear, with a low around 62.
Sunday
Sunny, with a high near 82.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Glen Carbon IL
 38.75°N 89.97°W (Elev. 499 ft)
Last Update:
2:16 am CDT Aug 18, 2025
Forecast Valid:
3am CDT Aug 18, 2025-6pm CDT Aug 24, 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