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.

Overcast

30°F

-1°C

Humidity 82%
Wind Speed S 9 mph
Barometer 30.16 in (1021.7 mb)
Dewpoint 25°F (-4°C)
Visibility 10.00 mi
Wind Chill22°F (-6°C)
Last update 3 Dec 10:52 am CST
Extended Forecast for

Saint Johns IL

  • Today

    Today: Cloudy, with a high near 36. South southwest wind 5 to 9 mph.

    High: 36 °F

    Cloudy

  • Tonight

    Tonight: Cloudy, with a low around 20. Light and variable wind becoming north 5 to 10 mph after midnight.

    Low: 20 °F

    Cloudy

  • Thursday

    Thursday: Cloudy through mid morning, then gradual clearing, with a high near 29. North wind 5 to 10 mph.

    High: 29 °F

    Gradual
    Clearing

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 18. Calm wind.

    Low: 18 °F

    Mostly Cloudy

  • Friday

    Friday: Mostly sunny, with a high near 41. Calm wind becoming south southwest around 6 mph in the morning.

    High: 41 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 26. Light south southwest wind.

    Low: 26 °F

    Partly Cloudy

  • Saturday

    Saturday: Partly sunny, with a high near 42. Calm wind becoming west around 6 mph.

    High: 42 °F

    Partly Sunny

  • Saturday Night

    Saturday Night: Mostly cloudy, with a low around 27. Calm wind becoming northeast around 5 mph after midnight.

    Low: 27 °F

    Mostly Cloudy

  • Sunday

    Sunday: A slight chance of showers after noon. Partly sunny, with a high near 42. Northeast wind 5 to 7 mph.

    High: 42 °F

    Mostly Cloudy
    then Slight
    Chance
    Showers

Detailed Forecast

Today
Cloudy, with a high near 36. South southwest wind 5 to 9 mph.
Tonight
Cloudy, with a low around 20. Light and variable wind becoming north 5 to 10 mph after midnight.
Thursday
Cloudy through mid morning, then gradual clearing, with a high near 29. North wind 5 to 10 mph.
Thursday Night
Mostly cloudy, with a low around 18. Calm wind.
Friday
Mostly sunny, with a high near 41. Calm wind becoming south southwest around 6 mph in the morning.
Friday Night
Partly cloudy, with a low around 26. Light south southwest wind.
Saturday
Partly sunny, with a high near 42. Calm wind becoming west around 6 mph.
Saturday Night
Mostly cloudy, with a low around 27. Calm wind becoming northeast around 5 mph after midnight.
Sunday
A slight chance of showers after noon. Partly sunny, with a high near 42. Northeast wind 5 to 7 mph.
Sunday Night
A slight chance of showers before midnight. Mostly cloudy, with a low around 24. North wind around 6 mph.
Monday
Partly sunny, with a high near 37. North northwest wind 5 to 7 mph becoming south in the afternoon.
Monday Night
Partly cloudy, with a low around 27. South southwest wind 3 to 7 mph.
Tuesday
Mostly sunny, with a high near 47. Southwest wind 7 to 11 mph.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Saint Johns IL
 38.03°N 89.24°W
Last Update:
10:16 am CST Dec 3, 2025
Forecast Valid:
11am CST Dec 3, 2025-6pm CST Dec 9, 2025
 
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