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

64°F

18°C

Humidity 56%
Wind Speed SW 9 mph
Barometer 29.75 in
Dewpoint 48°F (9°C)
Visibility 10.00 mi
Last update 6 Jan 3:45 pm CST
Extended Forecast for

Simpson IL

  • This Afternoon

    This Afternoon: Sunny, with a steady temperature around 61. West southwest wind around 7 mph.

    High: 61 °F

    Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 36. West southwest wind around 5 mph becoming calm in the evening.

    Low: 36 °F

    Mostly Clear

  • Wednesday

    Wednesday: Mostly sunny, with a high near 58. Calm wind becoming south around 5 mph in the afternoon.

    High: 58 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 45. Light southeast wind.

    Low: 45 °F

    Mostly Cloudy

  • Thursday

    Thursday: Showers likely, mainly after noon. Cloudy, with a high near 65. South southeast wind 5 to 13 mph, with gusts as high as 24 mph. Chance of precipitation is 70%.

    High: 65 °F

    Chance
    Showers then
    Showers
    Likely

  • Thursday Night

    Thursday Night: Showers and possibly a thunderstorm before 3am, then showers likely. Low around 57. South southwest wind 6 to 13 mph, with gusts as high as 24 mph. Chance of precipitation is 90%.

    Low: 57 °F

    Showers

  • Friday

    Friday: A 40 percent chance of showers. Mostly cloudy, with a high near 64. Southwest wind 5 to 8 mph becoming north northeast in the afternoon.

    High: 64 °F

    Chance
    Showers

  • Friday Night

    Friday Night: Showers likely, mainly before midnight. Mostly cloudy, with a low around 45. Calm wind becoming west around 6 mph after midnight.

    Low: 45 °F

    Showers
    Likely

  • Saturday

    Saturday: Partly sunny, with a high near 52. West wind 6 to 10 mph, with gusts as high as 21 mph.

    High: 52 °F

    Partly Sunny

Detailed Forecast

This Afternoon
Sunny, with a steady temperature around 61. West southwest wind around 7 mph.
Tonight
Mostly clear, with a low around 36. West southwest wind around 5 mph becoming calm in the evening.
Wednesday
Mostly sunny, with a high near 58. Calm wind becoming south around 5 mph in the afternoon.
Wednesday Night
Mostly cloudy, with a low around 45. Light southeast wind.
Thursday
Showers likely, mainly after noon. Cloudy, with a high near 65. South southeast wind 5 to 13 mph, with gusts as high as 24 mph. Chance of precipitation is 70%.
Thursday Night
Showers and possibly a thunderstorm before 3am, then showers likely. Low around 57. South southwest wind 6 to 13 mph, with gusts as high as 24 mph. Chance of precipitation is 90%.
Friday
A 40 percent chance of showers. Mostly cloudy, with a high near 64. Southwest wind 5 to 8 mph becoming north northeast in the afternoon.
Friday Night
Showers likely, mainly before midnight. Mostly cloudy, with a low around 45. Calm wind becoming west around 6 mph after midnight.
Saturday
Partly sunny, with a high near 52. West wind 6 to 10 mph, with gusts as high as 21 mph.
Saturday Night
Partly cloudy, with a low around 28. West northwest wind around 6 mph.
Sunday
Mostly sunny, with a high near 39. West northwest wind 3 to 7 mph.
Sunday Night
Mostly clear, with a low around 24. Calm wind.
Monday
Mostly sunny, with a high near 46. Calm wind becoming southwest 5 to 7 mph in the morning.
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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:
3:16 pm CST Jan 6, 2026
Forecast Valid:
4pm CST Jan 6, 2026-6pm CST Jan 12, 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