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Hazardous Weather Conditions

Current conditions at

Southern Illinois Airport (KMDH)

Lat: 37.78°NLon: 89.25°WElev: 400ft.

Fair

95°F

35°C

Humidity 44%
Wind Speed S 3 mph
Barometer 30.00 in (1015.4 mb)
Dewpoint 70°F (21°C)
Visibility 10.00 mi
Heat Index101°F (38°C)
Last update 18 Aug 3:52 pm CDT
Extended Forecast for

3 Miles NNW Royalton IL

Heat Advisory August 18, 03:58pm until August 19, 07:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 18, 03:58pm until August 19, 07:00pm

    NOW until 7:00pm Tue

    Heat Advisory

  • This Afternoon

    High: 98 °F

    Hot

  • Tonight

    Tonight: Clear, with a low around 76. Calm wind.

    Low: 76 °F

    Clear

  • Tuesday

    Tuesday: A 40 percent chance of showers and thunderstorms, mainly after 4pm. Sunny and hot, with a high near 98. Heat index values as high as 107. Calm wind becoming west around 5 mph in the morning.

    High: 98 °F

    Sunny then
    Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 72. Light and variable wind.

    Low: 72 °F

    Chance
    T-storms

  • Wednesday

    Wednesday: A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 90. Light north northeast wind increasing to 5 to 10 mph in the morning.

    High: 90 °F

    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 68. North northeast wind 6 to 9 mph.

    Low: 68 °F

    Partly Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 89. North northeast wind 6 to 10 mph.

    High: 89 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 67. North northeast wind 5 to 7 mph becoming calm in the evening.

    Low: 67 °F

    Mostly Clear

Detailed Forecast

This Afternoon
Sunny and hot, with a high near 98. Heat index values as high as 105. Light southeast wind.
Tonight
Clear, with a low around 76. Calm wind.
Tuesday
A 40 percent chance of showers and thunderstorms, mainly after 4pm. Sunny and hot, with a high near 98. Heat index values as high as 107. Calm wind becoming west around 5 mph in the morning.
Tuesday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 72. Light and variable wind.
Wednesday
A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 90. Light north northeast wind increasing to 5 to 10 mph in the morning.
Wednesday Night
Partly cloudy, with a low around 68. North northeast wind 6 to 9 mph.
Thursday
Mostly sunny, with a high near 89. North northeast wind 6 to 10 mph.
Thursday Night
Mostly clear, with a low around 67. North northeast wind 5 to 7 mph becoming calm in the evening.
Friday
Sunny, with a high near 92. Calm wind becoming north northeast around 6 mph in the afternoon.
Friday Night
Mostly clear, with a low around 67. North wind around 5 mph becoming calm in the evening.
Saturday
Sunny, with a high near 91. Calm wind becoming north northwest 5 to 8 mph in the afternoon.
Saturday Night
Mostly clear, with a low around 63. North wind 3 to 6 mph.
Sunday
Sunny, with a high near 85. Light north wind becoming north northwest 5 to 10 mph in the morning.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
3 Miles NNW Royalton IL
 37.92°N 89.13°W
Last Update:
2:30 pm CDT Aug 18, 2025
Forecast Valid:
3pm CDT Aug 18, 2025-6pm CDT Aug 24, 2025
 
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Additional Resources

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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