National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce
Current conditions at

Southern Illinois Airport (KMDH)

Lat: 37.78°NLon: 89.25°WElev: 400ft.

Fair

76°F

24°C

Humidity 37%
Wind Speed W 8 mph
Barometer 30.00 in (1015.6 mb)
Dewpoint 48°F (9°C)
Visibility 10.00 mi
Heat Index78°F (26°C)
Last update 7 Oct 10:52 am CDT
Extended Forecast for

Saint Johns IL

  • Today

    Today: Sunny, with a high near 88. West southwest wind 6 to 9 mph.

    High: 88 °F

    Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 56. Light and variable wind.

    Low: 56 °F

    Mostly Clear

  • Thursday

    Thursday: Sunny, with a high near 85. Light and variable wind.

    High: 85 °F

    Sunny

  • Thursday Night

    Thursday Night: Clear, with a low around 53. Calm wind.

    Low: 53 °F

    Clear

  • Friday

    Friday: Sunny, with a high near 87. Calm wind becoming south southeast 5 to 8 mph in the morning.

    High: 87 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 59. South southeast wind around 5 mph becoming calm in the evening.

    Low: 59 °F

    Mostly Clear

  • Saturday

    Saturday: A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 84. Light south wind becoming south southeast 6 to 11 mph in the morning.

    High: 84 °F

    Sunny then
    Slight Chance
    Showers

  • Saturday Night

    Saturday Night: A chance of showers, then showers likely and possibly a thunderstorm after 1am. Partly cloudy, with a low around 58. Southeast wind around 7 mph becoming east northeast after midnight.

    Low: 58 °F

    Showers
    Likely

  • Sunday

    Sunday: A chance of showers, mainly before 1pm. Partly sunny, with a high near 78. East northeast wind 9 to 14 mph becoming north in the afternoon.

    High: 78 °F

    Chance
    Showers

Detailed Forecast

Today
Sunny, with a high near 88. West southwest wind 6 to 9 mph.
Tonight
Mostly clear, with a low around 56. Light and variable wind.
Thursday
Sunny, with a high near 85. Light and variable wind.
Thursday Night
Clear, with a low around 53. Calm wind.
Friday
Sunny, with a high near 87. Calm wind becoming south southeast 5 to 8 mph in the morning.
Friday Night
Mostly clear, with a low around 59. South southeast wind around 5 mph becoming calm in the evening.
Saturday
A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 84. Light south wind becoming south southeast 6 to 11 mph in the morning.
Saturday Night
A chance of showers, then showers likely and possibly a thunderstorm after 1am. Partly cloudy, with a low around 58. Southeast wind around 7 mph becoming east northeast after midnight.
Sunday
A chance of showers, mainly before 1pm. Partly sunny, with a high near 78. East northeast wind 9 to 14 mph becoming north in the afternoon.
Sunday Night
Partly cloudy, with a low around 56. North wind around 5 mph becoming calm in the evening.
Columbus Day
Mostly sunny, with a high near 81. Calm wind becoming southwest 5 to 8 mph in the afternoon.
Monday Night
Partly cloudy, with a low around 58. South wind around 5 mph.
Tuesday
A slight chance of showers. Mostly sunny, with a high near 83. Southwest wind 5 to 13 mph.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Saint Johns IL
 38.03°N 89.21°W
Last Update:
9:16 am CDT Oct 7, 2026
Forecast Valid:
11am CDT Oct 7, 2026-6pm CDT Oct 13, 2026
 
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Additional Resources

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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