Dangerous Heat in the Central and Southern U.S.; Thunderstorms and Heavy Rain in the Northern Plains

Dangerous, prolonged heat is expected across portions of the Central and Southeast U.S. through July. Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley Tuesday, with damaging winds and large hail as the primary threats. Heavy rainfall could lead to areas of flooding across the northern Plains, Upper Midwest, Southeast and Southwest. Read More >

Current conditions at

Marion - Williamson County Regional Airport (KMWA)

Lat: 37.77°NLon: 89.01°WElev: 486ft.

Fair

78°F

26°C

Humidity 96%
Wind Speed Calm
Barometer 30.00 in
Dewpoint 76°F (24°C)
Visibility 10.00 mi
Heat Index81°F (27°C)
Last update 21 Jul 8:55 pm CDT
Extended Forecast for

Simpson IL

Extreme Heat Warning July 21, 09:09pm until July 24, 07:00pm
Click here for hazard details and duration
Extreme Heat Warning
  •  
    Extreme Heat Warning July 21, 09:09pm until July 24, 07:00pm

    NOW until 7:00pm Thu

    Extreme Heat Warning

  • Tonight

    Low: 74 °F

    Mostly Cloudy
    then Patchy
    Fog

  • Tuesday

    Tuesday: A 20 percent chance of showers and thunderstorms after 4pm.  Patchy fog before 8am.  Otherwise, mostly sunny, with a high near 93. Heat index values as high as 106. Calm wind becoming east around 5 mph in the afternoon.

    High: 93 °F

    Patchy Fog
    then Slight
    Chance
    T-storms

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 75. Light east wind.

    Low: 75 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny, with a high near 95. Heat index values as high as 109. Calm wind.

    High: 95 °F

    Sunny

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 75. Calm wind.

    Low: 75 °F

    Mostly Clear

  • Thursday

    Thursday: Mostly sunny, with a high near 94. Calm wind becoming south around 5 mph in the afternoon.

    High: 94 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 75. Calm wind.

    Low: 75 °F

    Mostly Clear

  • Friday

    Friday: A slight chance of showers and thunderstorms after 1pm.  Mostly sunny, with a high near 93. Calm wind becoming south southwest around 6 mph in the morning.

    High: 93 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

Detailed Forecast

Tonight
Patchy fog after 2am. Otherwise, mostly cloudy, with a low around 74. Calm wind.
Tuesday
A 20 percent chance of showers and thunderstorms after 4pm. Patchy fog before 8am. Otherwise, mostly sunny, with a high near 93. Heat index values as high as 106. Calm wind becoming east around 5 mph in the afternoon.
Tuesday Night
Mostly clear, with a low around 75. Light east wind.
Wednesday
Sunny, with a high near 95. Heat index values as high as 109. Calm wind.
Wednesday Night
Mostly clear, with a low around 75. Calm wind.
Thursday
Mostly sunny, with a high near 94. Calm wind becoming south around 5 mph in the afternoon.
Thursday Night
Mostly clear, with a low around 75. Calm wind.
Friday
A slight chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 93. Calm wind becoming south southwest around 6 mph in the morning.
Friday Night
A slight chance of showers and thunderstorms. Partly cloudy, with a low around 75. Calm wind.
Saturday
A chance of showers and thunderstorms, mainly after 1pm. Mostly sunny, with a high near 93. Calm wind becoming south southwest around 6 mph in the morning.
Saturday Night
A slight chance of showers and thunderstorms. Partly cloudy, with a low around 76. Calm wind.
Sunday
A chance of showers and thunderstorms. Mostly sunny, with a high near 93. Light southwest wind.
Sunday Night
Mostly clear, with a low around 74. Calm wind.
Monday
A slight chance of showers and thunderstorms. Sunny, with a high near 93. Light and variable wind.
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ABOUT THIS FORECAST

 
Point Forecast:
Simpson IL
 37.46°N 88.77°W
7:31 pm CDT Jul 21, 2025
9pm CDT Jul 21, 2025-6pm CDT Jul 28, 2025
 
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Additional Resources

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