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

79°F

26°C

Humidity 61%
Wind Speed S 6 mph
Barometer 29.92 in
Dewpoint 64°F (18°C)
Visibility 10.00 mi
Heat Index81°F (27°C)
Last update 16 May 5:47 pm CDT
Extended Forecast for

Simpson IL

  • Tonight

    Tonight: A slight chance of showers and thunderstorms before 7pm, then a slight chance of showers between 7pm and 8pm. Partly cloudy, with a low around 66. South southeast wind 3 to 8 mph. Chance of precipitation is 20%.

    Low: 66 °F

    Slight Chance
    T-storms then
    Partly Cloudy

  • Sunday

    Sunday: Partly sunny, then gradually becoming sunny, with a high near 88. South wind 5 to 13 mph, with gusts as high as 23 mph.

    High: 88 °F

    Becoming
    Sunny

  • Sunday Night

    Sunday Night: Increasing clouds, with a low around 68. South wind 6 to 8 mph, with gusts as high as 20 mph.

    Low: 68 °F

    Increasing
    Clouds

  • Monday

    Monday: A 30 percent chance of showers and thunderstorms after 1pm. Increasing clouds, with a high near 89. South wind 8 to 14 mph, with gusts as high as 25 mph.

    High: 89 °F

    Mostly Sunny
    then Chance
    T-storms

  • Monday Night

    Monday Night: Partly cloudy, with a low around 70. South wind 7 to 9 mph, with gusts as high as 21 mph.

    Low: 70 °F

    Partly Cloudy

  • Tuesday

    Tuesday: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Partly sunny, with a high near 88. South southwest wind 8 to 13 mph, with gusts as high as 25 mph. Chance of precipitation is 70%.

    High: 88 °F

    Chance
    T-storms then
    Showers
    Likely

  • Tuesday Night

    Tuesday Night: Showers and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms after 1am. Low around 65. South southwest wind 5 to 7 mph becoming calm in the evening. Chance of precipitation is 80%.

    Low: 65 °F

    Showers

  • Wednesday

    Wednesday: A chance of showers and thunderstorms. Mostly cloudy, with a high near 78. North wind 3 to 8 mph.

    High: 78 °F

    Chance
    Showers

  • Wednesday Night

    Wednesday Night: A chance of showers. Mostly cloudy, with a low around 56. North northeast wind 3 to 7 mph.

    Low: 56 °F

    Chance
    Showers

Detailed Forecast

Tonight
A slight chance of showers and thunderstorms before 7pm, then a slight chance of showers between 7pm and 8pm. Partly cloudy, with a low around 66. South southeast wind 3 to 8 mph. Chance of precipitation is 20%.
Sunday
Partly sunny, then gradually becoming sunny, with a high near 88. South wind 5 to 13 mph, with gusts as high as 23 mph.
Sunday Night
Increasing clouds, with a low around 68. South wind 6 to 8 mph, with gusts as high as 20 mph.
Monday
A 30 percent chance of showers and thunderstorms after 1pm. Increasing clouds, with a high near 89. South wind 8 to 14 mph, with gusts as high as 25 mph.
Monday Night
Partly cloudy, with a low around 70. South wind 7 to 9 mph, with gusts as high as 21 mph.
Tuesday
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Partly sunny, with a high near 88. South southwest wind 8 to 13 mph, with gusts as high as 25 mph. Chance of precipitation is 70%.
Tuesday Night
Showers and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms after 1am. Low around 65. South southwest wind 5 to 7 mph becoming calm in the evening. Chance of precipitation is 80%.
Wednesday
A chance of showers and thunderstorms. Mostly cloudy, with a high near 78. North wind 3 to 8 mph.
Wednesday Night
A chance of showers. Mostly cloudy, with a low around 56. North northeast wind 3 to 7 mph.
Thursday
A slight chance of showers. Partly sunny, with a high near 74. North northeast wind 6 to 8 mph.
Thursday Night
A slight chance of showers. Mostly cloudy, with a low around 56. North northeast wind around 6 mph becoming calm in the evening.
Friday
A chance of showers. Partly sunny, with a high near 77. Northeast wind 3 to 6 mph.
Friday Night
A slight chance of showers. Mostly cloudy, with a low around 59. Light northeast wind.
Saturday
A chance of showers and thunderstorms. Partly sunny, with a high near 82. Calm wind becoming east northeast around 6 mph in the afternoon.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Simpson IL
 37.46°N 88.77°W
Last Update:
6:26 pm CDT May 16, 2026
Forecast Valid:
6pm CDT May 16, 2026-6pm CDT May 23, 2026
 
Forecast Discussion
 
Get as KML Get as XML

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