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

Hazardous Weather Conditions

Current conditions at

Marion - Williamson County Regional Airport (KMWA)

Lat: 37.77°NLon: 89.01°WElev: 486ft.

Fair

93°F

34°C

Humidity 47%
Wind Speed S 12 mph
Barometer 30.01 in
Dewpoint 70°F (21°C)
Visibility 10.00 mi
Heat Index99°F (37°C)
Last update 1 Sep 5:45 pm CDT
Extended Forecast for

Carterville IL

Extreme Heat Warning until September 5, 08:00pm
Click here for hazard details and duration
Extreme Heat Warning
  •  
    Extreme Heat Warning until September 5, 08:00pm

    NOW until 8:00pm Sat

    Extreme Heat Warning

  • Tonight

    Low: 76 °F

    Clear

  • Wednesday

    Wednesday: Sunny and hot, with a high near 99. Heat index values as high as 105. Calm wind becoming south southwest 5 to 7 mph in the morning.

    High: 99 °F

    Hot

  • Wednesday Night

    Wednesday Night: Clear, with a low around 77. South wind around 5 mph becoming calm in the evening.

    Low: 77 °F

    Clear

  • Thursday

    Thursday: Sunny and hot, with a high near 99. Heat index values as high as 105. Calm wind becoming southwest 5 to 7 mph in the afternoon.

    High: 99 °F

    Hot

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 76. Light south wind.

    Low: 76 °F

    Mostly Clear

  • Friday

    Friday: Sunny and hot, with a high near 99. Light and variable wind.

    High: 99 °F

    Hot

  • Friday Night

    Friday Night: Mostly clear, with a low around 75. Calm wind.

    Low: 75 °F

    Mostly Clear

  • Saturday

    Saturday: A slight chance of showers and thunderstorms. Mostly sunny and hot, with a high near 98. Light and variable wind.

    High: 98 °F

    Slight Chance
    T-storms

Detailed Forecast

Tonight
Clear, with a low around 76. Light and variable wind.
Wednesday
Sunny and hot, with a high near 99. Heat index values as high as 105. Calm wind becoming south southwest 5 to 7 mph in the morning.
Wednesday Night
Clear, with a low around 77. South wind around 5 mph becoming calm in the evening.
Thursday
Sunny and hot, with a high near 99. Heat index values as high as 105. Calm wind becoming southwest 5 to 7 mph in the afternoon.
Thursday Night
Mostly clear, with a low around 76. Light south wind.
Friday
Sunny and hot, with a high near 99. Light and variable wind.
Friday Night
Mostly clear, with a low around 75. Calm wind.
Saturday
A slight chance of showers and thunderstorms. Mostly sunny and hot, with a high near 98. Light and variable wind.
Saturday Night
Partly cloudy, with a low around 73. Calm wind.
Sunday
A slight chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 95. Calm wind becoming north northeast 5 to 7 mph in the afternoon.
Sunday Night
Mostly clear, with a low around 70. Light east wind.
Labor Day
Mostly sunny, with a high near 93. Calm wind becoming east southeast around 6 mph in the afternoon.
Monday Night
Partly cloudy, with a low around 68. East southeast wind around 5 mph becoming calm in the evening.
Tuesday
Mostly sunny, with a high near 92. South southwest wind 3 to 6 mph.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Carterville IL
 37.76°N 89.09°W
Last Update:
5:56 pm CDT Sep 1, 2026
Forecast Valid:
6pm CDT Sep 1, 2026-6pm CDT Sep 8, 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