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

Marion - Williamson County Regional Airport (KMWA)

Lat: 37.77°NLon: 89.01°WElev: 486ft.

Fair

82°F

28°C

Humidity 40%
Wind Speed S 6 mph
Barometer 29.98 in
Dewpoint 55°F (13°C)
Visibility 10.00 mi
Heat Index81°F (27°C)
Last update 11 Oct 3:45 pm CDT
Extended Forecast for

Simpson IL

  • This Afternoon

    This Afternoon: Sunny, with a high near 83. West northwest wind around 5 mph.

    High: 83 °F

    Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 59. Calm wind.

    Low: 59 °F

    Mostly Clear

  • Columbus Day

    Columbus Day: Sunny, with a high near 90. Light south southwest wind becoming southwest 5 to 10 mph in the morning. Winds could gust as high as 18 mph.

    High: 90 °F

    Sunny

  • Monday Night

    Monday Night: Clear, with a low around 63. South southwest wind 3 to 5 mph.

    Low: 63 °F

    Clear

  • Tuesday

    Tuesday: Sunny, with a high near 91. Southwest wind 5 to 9 mph.

    High: 91 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 68. Light south southwest wind.

    Low: 68 °F

    Mostly Clear

  • Wednesday

    Wednesday: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Mostly sunny, with a high near 88. Calm wind becoming southwest around 6 mph in the morning. Chance of precipitation is 70%.

    High: 88 °F

    Chance
    T-storms then
    Showers
    Likely

  • Wednesday Night

    Wednesday Night: Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 65. Calm wind.

    Low: 65 °F

    Showers
    Likely

  • Thursday

    Thursday: A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 83. Calm wind becoming south southeast 5 to 8 mph in the morning.

    High: 83 °F

    Chance
    Showers

Detailed Forecast

This Afternoon
Sunny, with a high near 83. West northwest wind around 5 mph.
Tonight
Mostly clear, with a low around 59. Calm wind.
Columbus Day
Sunny, with a high near 90. Light south southwest wind becoming southwest 5 to 10 mph in the morning. Winds could gust as high as 18 mph.
Monday Night
Clear, with a low around 63. South southwest wind 3 to 5 mph.
Tuesday
Sunny, with a high near 91. Southwest wind 5 to 9 mph.
Tuesday Night
Mostly clear, with a low around 68. Light south southwest wind.
Wednesday
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Mostly sunny, with a high near 88. Calm wind becoming southwest around 6 mph in the morning. Chance of precipitation is 70%.
Wednesday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 65. Calm wind.
Thursday
A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 83. Calm wind becoming south southeast 5 to 8 mph in the morning.
Thursday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 58. Calm wind becoming west northwest 5 to 8 mph after midnight.
Friday
Partly sunny, with a high near 70. North northwest wind 13 to 15 mph, with gusts as high as 25 mph.
Friday Night
Partly cloudy, with a low around 41. North wind 9 to 15 mph, with gusts as high as 25 mph.
Saturday
Sunny, with a high near 61. North wind 9 to 11 mph.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Simpson IL
 37.46°N 88.77°W
Last Update:
2:01 pm CDT Oct 11, 2026
Forecast Valid:
4pm CDT Oct 11, 2026-6pm CDT Oct 17, 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