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.

Fair

77°F

25°C

Humidity 90%
Wind Speed S 7 mph
Barometer 30.07 in
Dewpoint 74°F (23°C)
Visibility 10.00 mi
Heat Index78°F (26°C)
Last update 15 Aug 5:15 am CDT
Extended Forecast for

Royalton IL

Extreme Heat Warning August 15, 05:31am until August 16, 08:00pm
Click here for hazard details and duration
Extreme Heat Warning
  •  
    Extreme Heat Warning August 15, 05:31am until August 16, 08:00pm

    NOW until 8:00pm Sun

    Extreme Heat Warning

  • Today

    High: 97 °F

    Hot

  • Tonight

    Tonight: Clear, with a low around 76. South southwest wind 3 to 6 mph.

    Low: 76 °F

    Clear

  • Sunday

    Sunday: Mostly sunny and hot, with a high near 98. Heat index values as high as 110. West wind 5 to 8 mph.

    High: 98 °F

    Hot

  • Sunday Night

    Sunday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 73. North northwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 50%.

    Low: 73 °F

    Chance
    T-storms

  • Monday

    Monday: Mostly sunny, with a high near 89. North wind 3 to 8 mph.

    High: 89 °F

    Mostly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 68. North wind around 5 mph becoming calm in the evening.

    Low: 68 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Sunny, with a high near 91. Calm wind.

    High: 91 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 72. Calm wind becoming south 5 to 7 mph after midnight.

    Low: 72 °F

    Mostly Clear

Detailed Forecast

Today
Sunny and hot, with a high near 97. Heat index values as high as 107. Light and variable wind becoming south southwest 5 to 7 mph in the morning.
Tonight
Clear, with a low around 76. South southwest wind 3 to 6 mph.
Sunday
Mostly sunny and hot, with a high near 98. Heat index values as high as 110. West wind 5 to 8 mph.
Sunday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 73. North northwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 50%.
Monday
Mostly sunny, with a high near 89. North wind 3 to 8 mph.
Monday Night
Partly cloudy, with a low around 68. North wind around 5 mph becoming calm in the evening.
Tuesday
Sunny, with a high near 91. Calm wind.
Tuesday Night
Mostly clear, with a low around 72. Calm wind becoming south 5 to 7 mph after midnight.
Wednesday
A slight chance of showers and thunderstorms. Partly sunny, with a high near 95. South southwest wind 6 to 13 mph becoming west northwest in the afternoon. Winds could gust as high as 20 mph.
Wednesday Night
A slight chance of showers and thunderstorms. Partly cloudy, with a low around 69. North wind 6 to 11 mph.
Thursday
A slight chance of showers and thunderstorms. Mostly sunny, with a high near 86. North northeast wind 5 to 9 mph.
Thursday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 64. East northeast wind 3 to 7 mph.
Friday
A slight chance of showers and thunderstorms. Mostly sunny, with a high near 84. East northeast wind 3 to 8 mph.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Royalton IL
 37.87°N 89.11°W
Last Update:
5:26 am CDT Aug 15, 2026
Forecast Valid:
5am CDT Aug 15, 2026-6pm CDT Aug 21, 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