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.

Partly Cloudy

46°F

8°C

Humidity 97%
Wind Speed Calm
Barometer 30.11 in
Dewpoint 46°F (8°C)
Visibility 10.00 mi
Last update 2 May 8:15 pm CDT
Extended Forecast for

Simpson IL

  • Tonight

    Tonight: Mostly clear, with a low around 37. Light and variable wind.

    Low: 37 °F

    Mostly Clear

  • Sunday

    Sunday: Patchy frost before 7am. Otherwise, sunny, with a high near 70. Light south southwest wind becoming southwest 6 to 11 mph in the morning. Winds could gust as high as 22 mph.

    High: 70 °F

    Patchy Frost
    then Sunny

  • Sunday Night

    Sunday Night: A chance of showers and thunderstorms. Partly cloudy, with a low around 55. South southwest wind 5 to 8 mph, with gusts as high as 18 mph. Chance of precipitation is 40%.

    Low: 55 °F

    Slight Chance
    T-storms then
    Chance
    Showers

  • Monday

    Monday: A slight chance of showers, with thunderstorms also possible after 1pm. Mostly sunny, with a high near 80. Southwest wind 6 to 14 mph, with gusts as high as 26 mph. Chance of precipitation is 20%.

    High: 80 °F

    Slight Chance
    Showers then
    Slight Chance
    T-storms

  • Monday Night

    Monday Night: A chance of showers between 1am and 4am, then a chance of showers and thunderstorms after 4am. Partly cloudy, with a low around 58. South southwest wind 8 to 10 mph, with gusts as high as 22 mph. Chance of precipitation is 40%.

    Low: 58 °F

    Partly Cloudy
    then Chance
    Showers

  • Tuesday

    Tuesday: Showers and possibly a thunderstorm. High near 72. South southwest wind 8 to 14 mph, with gusts as high as 25 mph. Chance of precipitation is 80%.

    High: 72 °F

    Showers

  • Tuesday Night

    Tuesday Night: Showers and possibly a thunderstorm. Low around 50. South southwest wind 6 to 10 mph becoming north after midnight. Winds could gust as high as 22 mph. Chance of precipitation is 90%.

    Low: 50 °F

    Showers

  • Wednesday

    Wednesday: Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 62. North northeast wind 3 to 7 mph.

    High: 62 °F

    Showers
    Likely

  • Wednesday Night

    Wednesday Night: A chance of showers, mainly before 1am. Mostly cloudy, with a low around 45. North northwest wind 5 to 7 mph.

    Low: 45 °F

    Chance
    Showers

Detailed Forecast

Tonight
Mostly clear, with a low around 37. Light and variable wind.
Sunday
Patchy frost before 7am. Otherwise, sunny, with a high near 70. Light south southwest wind becoming southwest 6 to 11 mph in the morning. Winds could gust as high as 22 mph.
Sunday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 55. South southwest wind 5 to 8 mph, with gusts as high as 18 mph. Chance of precipitation is 40%.
Monday
A slight chance of showers, with thunderstorms also possible after 1pm. Mostly sunny, with a high near 80. Southwest wind 6 to 14 mph, with gusts as high as 26 mph. Chance of precipitation is 20%.
Monday Night
A chance of showers between 1am and 4am, then a chance of showers and thunderstorms after 4am. Partly cloudy, with a low around 58. South southwest wind 8 to 10 mph, with gusts as high as 22 mph. Chance of precipitation is 40%.
Tuesday
Showers and possibly a thunderstorm. High near 72. South southwest wind 8 to 14 mph, with gusts as high as 25 mph. Chance of precipitation is 80%.
Tuesday Night
Showers and possibly a thunderstorm. Low around 50. South southwest wind 6 to 10 mph becoming north after midnight. Winds could gust as high as 22 mph. Chance of precipitation is 90%.
Wednesday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 62. North northeast wind 3 to 7 mph.
Wednesday Night
A chance of showers, mainly before 1am. Mostly cloudy, with a low around 45. North northwest wind 5 to 7 mph.
Thursday
Mostly sunny, with a high near 65. Northwest wind 5 to 9 mph, with gusts as high as 18 mph.
Thursday Night
Mostly clear, with a low around 45. Calm wind.
Friday
Mostly sunny, with a high near 72. Calm wind becoming south southwest 5 to 8 mph in the morning.
Friday Night
A slight chance of showers and thunderstorms. Partly cloudy, with a low around 53. Light south wind.
Saturday
Mostly sunny, with a high near 78. Calm wind becoming west southwest 5 to 7 mph in the afternoon.
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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:
4:31 pm CDT May 2, 2026
Forecast Valid:
8pm CDT May 2, 2026-6pm CDT May 9, 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