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.

Overcast

59°F

15°C

Humidity 94%
Wind Speed SE 12 mph
Barometer 30.22 in
Dewpoint 57°F (14°C)
Visibility 10.00 mi
Last update 1 Nov 1:45 pm CST
Extended Forecast for

Simpson IL

  • This Afternoon

    This Afternoon: A 50 percent chance of rain. Cloudy, with a high near 58. Southeast wind around 8 mph.

    High: 58 °F

    Chance Rain

  • Tonight

    Tonight: Rain likely, mainly after 5am. Cloudy, with a low around 55. South southeast wind 3 to 6 mph. Chance of precipitation is 60%.

    Low: 55 °F

    Rain Likely

  • Monday

    Monday: A chance of rain before 9am, then a slight chance of showers between 9am and noon. Cloudy, with a high near 71. South southeast wind 6 to 10 mph, with gusts as high as 20 mph. Chance of precipitation is 40%.

    High: 71 °F

    Chance Rain
    then Mostly
    Cloudy

  • Monday Night

    Monday Night: Mostly cloudy, with a low around 60. South wind 8 to 15 mph, with gusts as high as 25 mph.

    Low: 60 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: A 50 percent chance of showers after noon. Mostly cloudy, with a high near 77. South wind 15 to 17 mph, with gusts as high as 29 mph.

    High: 77 °F

    Mostly Cloudy
    then Chance
    Showers

  • Tuesday Night

    Tuesday Night: Showers and possibly a thunderstorm before midnight, then showers likely. Low around 57. South wind 6 to 14 mph, with gusts as high as 23 mph. Chance of precipitation is 90%.

    Low: 57 °F

    Showers

  • Wednesday

    Wednesday: A 40 percent chance of showers before noon. Partly sunny, with a high near 71. South southwest wind 5 to 10 mph.

    High: 71 °F

    Chance
    Showers then
    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 46. Calm wind.

    Low: 46 °F

    Partly Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 69. Calm wind becoming west southwest around 6 mph.

    High: 69 °F

    Mostly Sunny

Detailed Forecast

This Afternoon
A 50 percent chance of rain. Cloudy, with a high near 58. Southeast wind around 8 mph.
Tonight
Rain likely, mainly after 5am. Cloudy, with a low around 55. South southeast wind 3 to 6 mph. Chance of precipitation is 60%.
Monday
A chance of rain before 9am, then a slight chance of showers between 9am and noon. Cloudy, with a high near 71. South southeast wind 6 to 10 mph, with gusts as high as 20 mph. Chance of precipitation is 40%.
Monday Night
Mostly cloudy, with a low around 60. South wind 8 to 15 mph, with gusts as high as 25 mph.
Tuesday
A 50 percent chance of showers after noon. Mostly cloudy, with a high near 77. South wind 15 to 17 mph, with gusts as high as 29 mph.
Tuesday Night
Showers and possibly a thunderstorm before midnight, then showers likely. Low around 57. South wind 6 to 14 mph, with gusts as high as 23 mph. Chance of precipitation is 90%.
Wednesday
A 40 percent chance of showers before noon. Partly sunny, with a high near 71. South southwest wind 5 to 10 mph.
Wednesday Night
Partly cloudy, with a low around 46. Calm wind.
Thursday
Mostly sunny, with a high near 69. Calm wind becoming west southwest around 6 mph.
Thursday Night
Partly cloudy, with a low around 45. Calm wind.
Friday
Mostly sunny, with a high near 65. Calm wind becoming northwest 5 to 7 mph.
Friday Night
Partly cloudy, with a low around 40. Calm wind.
Saturday
Mostly sunny, with a high near 64. Calm wind becoming north northwest around 5 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:
12:26 pm CST Nov 1, 2026
Forecast Valid:
2pm CST Nov 1, 2026-6pm CST Nov 7, 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