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.

Mostly Cloudy

73°F

23°C

Humidity 89%
Wind Speed S 9 G 24 mph
Barometer 30.01 in
Dewpoint 70°F (21°C)
Visibility 10.00 mi
Last update 18 May 1:47 pm CDT
Extended Forecast for

Royalton IL

Lake Wind Advisory until May 18, 04:00pm
Click here for hazard details and duration
Lake Wind Advisory
  •  
    Lake Wind Advisory until May 18, 04:00pm

    NOW until 4:00pm Mon

    Lake Wind Advisory

  • This Afternoon

    High: 79 °F

    T-storms
    Likely

  • Tonight

    Tonight: A 40 percent chance of showers and thunderstorms, mainly before 9pm. Mostly cloudy, with a low around 70. South southeast wind 11 to 13 mph, with gusts as high as 22 mph.

    Low: 70 °F

    Chance
    T-storms then
    Partly Cloudy

  • Tuesday

    Tuesday: Showers and thunderstorms, mainly before 5pm, then showers and possibly a thunderstorm after 5pm. High near 86. South southwest wind 13 to 17 mph, with gusts as high as 25 mph. Chance of precipitation is 80%.

    High: 86 °F

    Chance
    Showers then
    T-storms

  • Tuesday Night

    Tuesday Night: Showers and thunderstorms likely before 1am, then showers likely and possibly a thunderstorm between 1am and 4am, then showers likely after 4am. Mostly cloudy, with a low around 62. West southwest wind 5 to 7 mph becoming calm. Chance of precipitation is 70%.

    Low: 62 °F

    T-storms
    Likely then
    Showers
    Likely

  • Wednesday

    Wednesday: Showers likely, with thunderstorms also possible after 4pm. Mostly cloudy, with a high near 72. North northeast wind around 10 mph. Chance of precipitation is 60%.

    High: 72 °F

    Showers
    Likely

  • Wednesday Night

    Wednesday Night: A slight chance of showers and thunderstorms before 7pm, then a slight chance of showers between 7pm and 1am. Mostly cloudy, with a low around 55. Northeast wind 7 to 10 mph. Chance of precipitation is 20%.

    Low: 55 °F

    Slight Chance
    T-storms then
    Slight Chance
    Showers

  • Thursday

    Thursday: Partly sunny, with a high near 75. Northeast wind 7 to 10 mph.

    High: 75 °F

    Partly Sunny

  • Thursday Night

    Thursday Night: A chance of showers, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 59. East northeast wind 7 to 10 mph.

    Low: 59 °F

    Showers
    Likely

Detailed Forecast

This Afternoon
Showers and thunderstorms likely before 4pm, then showers likely and possibly a thunderstorm after 4pm. Mostly cloudy, with a steady temperature around 79. South southwest wind 6 to 16 mph, with gusts as high as 25 mph. Chance of precipitation is 70%.
Tonight
A 40 percent chance of showers and thunderstorms, mainly before 9pm. Mostly cloudy, with a low around 70. South southeast wind 11 to 13 mph, with gusts as high as 22 mph.
Tuesday
Showers and thunderstorms, mainly before 5pm, then showers and possibly a thunderstorm after 5pm. High near 86. South southwest wind 13 to 17 mph, with gusts as high as 25 mph. Chance of precipitation is 80%.
Tuesday Night
Showers and thunderstorms likely before 1am, then showers likely and possibly a thunderstorm between 1am and 4am, then showers likely after 4am. Mostly cloudy, with a low around 62. West southwest wind 5 to 7 mph becoming calm. Chance of precipitation is 70%.
Wednesday
Showers likely, with thunderstorms also possible after 4pm. Mostly cloudy, with a high near 72. North northeast wind around 10 mph. Chance of precipitation is 60%.
Wednesday Night
A slight chance of showers and thunderstorms before 7pm, then a slight chance of showers between 7pm and 1am. Mostly cloudy, with a low around 55. Northeast wind 7 to 10 mph. Chance of precipitation is 20%.
Thursday
Partly sunny, with a high near 75. Northeast wind 7 to 10 mph.
Thursday Night
A chance of showers, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 59. East northeast wind 7 to 10 mph.
Friday
Showers and possibly a thunderstorm. Mostly cloudy, with a high near 77. East wind around 8 mph becoming south southwest in the afternoon.
Friday Night
Showers likely and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 62. South southwest wind 3 to 8 mph.
Saturday
A chance of showers and thunderstorms. Partly sunny, with a high near 81. Southwest wind 3 to 6 mph.
Saturday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 63. South wind around 5 mph becoming calm in the evening.
Sunday
A chance of showers and thunderstorms. Partly sunny, with a high near 83. Calm wind becoming south around 5 mph in the afternoon.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Royalton IL
 37.87°N 89.11°W
Last Update:
1:26 pm CDT May 18, 2026
Forecast Valid:
1pm CDT May 18, 2026-6pm CDT May 24, 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