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.

Heavy Drizzle

69°F

21°C

Humidity 98%
Wind Speed Calm
Barometer 29.70 in
Dewpoint 68°F (20°C)
Visibility 2.50 mi
Last update 2 Aug 12:35 am CDT
Extended Forecast for

Simpson IL

  • Overnight

    Overnight: A 30 percent chance of showers, mainly between 3am and 5am. Mostly cloudy, with a low around 66. Calm wind becoming west northwest around 5 mph.

    Low: 66 °F

    Chance
    Showers

  • Sunday

    Sunday: A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 80. North wind 7 to 10 mph, with gusts as high as 21 mph. Chance of precipitation is 40%.

    High: 80 °F

    Chance
    Showers

  • Sunday Night

    Sunday Night: A 10 percent chance of showers before 7pm. Partly cloudy, with a low around 66. North wind 5 to 7 mph becoming calm in the evening.

    Low: 66 °F

    Slight Chance
    Showers then
    Partly Cloudy

  • Monday

    Monday: Mostly sunny, with a high near 84. North wind 3 to 7 mph.

    High: 84 °F

    Mostly Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 66. Calm wind.

    Low: 66 °F

    Mostly Clear

  • Tuesday

    Tuesday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 86. Light north wind.

    High: 86 °F

    Sunny then
    Slight Chance
    T-storms

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 66. Calm wind.

    Low: 66 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny, with a high near 88. Light and variable wind.

    High: 88 °F

    Sunny

  • Wednesday Night

    Wednesday Night: A slight chance of showers and thunderstorms after 1am. Mostly clear, with a low around 69. Calm wind.

    Low: 69 °F

    Mostly Clear
    then Slight
    Chance
    T-storms

Detailed Forecast

Overnight
A 30 percent chance of showers, mainly between 3am and 5am. Mostly cloudy, with a low around 66. Calm wind becoming west northwest around 5 mph.
Sunday
A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 80. North wind 7 to 10 mph, with gusts as high as 21 mph. Chance of precipitation is 40%.
Sunday Night
A 10 percent chance of showers before 7pm. Partly cloudy, with a low around 66. North wind 5 to 7 mph becoming calm in the evening.
Monday
Mostly sunny, with a high near 84. North wind 3 to 7 mph.
Monday Night
Mostly clear, with a low around 66. Calm wind.
Tuesday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 86. Light north wind.
Tuesday Night
Mostly clear, with a low around 66. Calm wind.
Wednesday
Sunny, with a high near 88. Light and variable wind.
Wednesday Night
A slight chance of showers and thunderstorms after 1am. Mostly clear, with a low around 69. Calm wind.
Thursday
A slight chance of showers and thunderstorms before 1pm. Mostly sunny, with a high near 88. Calm wind becoming south around 5 mph in the afternoon.
Thursday Night
A slight chance of showers and thunderstorms. Partly cloudy, with a low around 71. Calm wind.
Friday
A slight chance of showers and thunderstorms. Mostly sunny, with a high near 90. Calm wind becoming south southwest 5 to 7 mph in the morning.
Friday Night
Partly cloudy, with a low around 71. Calm wind.
Saturday
A slight chance of showers and thunderstorms. Mostly sunny, with a high near 91. 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:
12:06 am CDT Aug 2, 2026
Forecast Valid:
12am CDT Aug 2, 2026-6pm CDT Aug 8, 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