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Hazardous Weather Conditions

Current conditions at

Southern Illinois Airport (KMDH)

Lat: 37.78°NLon: 89.25°WElev: 400ft.

Mostly Cloudy

72°F

22°C

Humidity 94%
Wind Speed S 9 mph
Barometer 29.98 in
Dewpoint 70°F (21°C)
Visibility 10.00 mi
Last update 19 Aug 11:49 am CDT
Extended Forecast for

Saint Johns IL

  • This Afternoon

    This Afternoon: A chance of showers and thunderstorms before 1pm, then a slight chance of showers and thunderstorms after 5pm. Partly sunny, with a high near 85. Southwest wind 5 to 7 mph becoming calm. Chance of precipitation is 30%.

    High: 85 °F

    Chance
    T-storms

  • Tonight

    Tonight: Showers and thunderstorms likely, mainly before 2am. Mostly cloudy, with a low around 67. Calm wind. Chance of precipitation is 70%.

    Low: 67 °F

    Showers
    Likely then
    Slight Chance
    T-storms

  • Thursday

    Thursday: Mostly cloudy, then gradually becoming sunny, with a high near 84. Calm wind becoming north northeast around 5 mph in the afternoon.

    High: 84 °F

    Decreasing
    Clouds

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 65. Calm wind.

    Low: 65 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 86. Calm wind.

    High: 86 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 66. Calm wind.

    Low: 66 °F

    Mostly Clear

  • Saturday

    Saturday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 86. Calm wind becoming northwest 5 to 7 mph in the afternoon.

    High: 86 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 65. Calm wind.

    Low: 65 °F

    Mostly Clear

  • Sunday

    Sunday: Mostly sunny, with a high near 84. Calm wind becoming north northwest around 6 mph in the afternoon.

    High: 84 °F

    Mostly Sunny

Detailed Forecast

This Afternoon
A chance of showers and thunderstorms before 1pm, then a slight chance of showers and thunderstorms after 5pm. Partly sunny, with a high near 85. Southwest wind 5 to 7 mph becoming calm. Chance of precipitation is 30%.
Tonight
Showers and thunderstorms likely, mainly before 2am. Mostly cloudy, with a low around 67. Calm wind. Chance of precipitation is 70%.
Thursday
Mostly cloudy, then gradually becoming sunny, with a high near 84. Calm wind becoming north northeast around 5 mph in the afternoon.
Thursday Night
Mostly clear, with a low around 65. Calm wind.
Friday
Sunny, with a high near 86. Calm wind.
Friday Night
Mostly clear, with a low around 66. Calm wind.
Saturday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 86. Calm wind becoming northwest 5 to 7 mph in the afternoon.
Saturday Night
Mostly clear, with a low around 65. Calm wind.
Sunday
Mostly sunny, with a high near 84. Calm wind becoming north northwest around 6 mph in the afternoon.
Sunday Night
A slight chance of showers after 1am. Partly cloudy, with a low around 64. Calm wind.
Monday
A slight chance of showers. Mostly sunny, with a high near 84. Calm wind becoming east southeast around 6 mph in the afternoon.
Monday Night
Partly cloudy, with a low around 66. East wind around 5 mph becoming calm in the evening.
Tuesday
Mostly sunny, with a high near 88. East wind 3 to 7 mph.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Saint Johns IL
 38.06°N 89.24°W
Last Update:
11:41 am CDT Aug 19, 2026
Forecast Valid:
12pm CDT Aug 19, 2026-6pm CDT Aug 25, 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