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

90°F

32°C

Humidity 59%
Wind Speed S 5 mph
Barometer 30.26 in
Dewpoint 73°F (23°C)
Visibility 10.00 mi
Heat Index99°F (37°C)
Last update 16 Sep 12:45 pm CDT
Extended Forecast for

Simpson IL

Heat Advisory September 16, 01:39pm until September 20, 07:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory September 16, 01:39pm until September 20, 07:00pm

    NOW until 7:00pm Sun

    Heat Advisory

  • This Afternoon

    High: 97 °F

    Hot

  • Tonight

    Tonight: Mostly clear, with a low around 73. Calm wind.

    Low: 73 °F

    Mostly Clear

  • Thursday

    Thursday: Sunny and hot, with a high near 98. Calm wind becoming west southwest around 5 mph.

    High: 98 °F

    Hot

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 73. Calm wind.

    Low: 73 °F

    Mostly Clear

  • Friday

    Friday: Sunny and hot, with a high near 97. Calm wind.

    High: 97 °F

    Hot

  • Friday Night

    Friday Night: Mostly clear, with a low around 71. Calm wind.

    Low: 71 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny and hot, with a high near 98. Calm wind becoming west southwest 5 to 7 mph in the morning.

    High: 98 °F

    Hot

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 71. Calm wind.

    Low: 71 °F

    Mostly Clear

Detailed Forecast

This Afternoon
Sunny and hot, with a high near 97. South southwest wind around 6 mph.
Tonight
Mostly clear, with a low around 73. Calm wind.
Thursday
Sunny and hot, with a high near 98. Calm wind becoming west southwest around 5 mph.
Thursday Night
Mostly clear, with a low around 73. Calm wind.
Friday
Sunny and hot, with a high near 97. Calm wind.
Friday Night
Mostly clear, with a low around 71. Calm wind.
Saturday
Sunny and hot, with a high near 98. Calm wind becoming west southwest 5 to 7 mph in the morning.
Saturday Night
Mostly clear, with a low around 71. Calm wind.
Sunday
Mostly sunny and hot, with a high near 97. Calm wind becoming west around 6 mph in the afternoon.
Sunday Night
Partly cloudy, with a low around 70. Calm wind.
Monday
A slight chance of showers and thunderstorms. Partly sunny, with a high near 93. Calm wind becoming west around 6 mph in the afternoon.
Monday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 66. Calm wind.
Tuesday
A slight chance of showers. Mostly sunny, with a high near 87. Calm wind becoming north around 6 mph in the morning.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Simpson IL
 37.46°N 88.77°W
Last Update:
1:26 pm CDT Sep 16, 2026
Forecast Valid:
1pm CDT Sep 16, 2026-6pm CDT Sep 22, 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