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.

Fog/Mist

29°F

-2°C

Humidity 92%
Wind Speed NW 3 mph
Barometer 30.24 in (1024.5 mb)
Dewpoint 27°F (-3°C)
Visibility 6.00 mi
Last update 4 Dec 12:52 am CST
Extended Forecast for

Saint Johns IL

  • Overnight

    Overnight: A 20 percent chance of snow before 3am. Mostly cloudy, with a low around 23. North wind 6 to 10 mph.

    Low: 23 °F

    Slight Chance
    Snow

  • Thursday

    Thursday: Partly sunny, with a high near 30. North wind 5 to 10 mph.

    High: 30 °F

    Partly Sunny

  • Thursday Night

    Thursday Night: Mostly cloudy, then gradually becoming mostly clear, with a low around 17. Light north wind.

    Low: 17 °F

    Decreasing
    Clouds

  • Friday

    Friday: Sunny, with a high near 41. Calm wind becoming south 5 to 7 mph in the afternoon.

    High: 41 °F

    Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 26. Southwest wind 3 to 6 mph.

    Low: 26 °F

    Partly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 43. Calm wind becoming west around 5 mph.

    High: 43 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: A slight chance of freezing rain after midnight. Mostly cloudy, with a low around 28. East northeast wind 3 to 6 mph. Chance of precipitation is 20%.

    Low: 28 °F

    Mostly Cloudy
    then Slight
    Chance
    Freezing Rain

  • Sunday

    Sunday: A slight chance of showers before noon. Mostly cloudy, with a high near 38. North wind 6 to 9 mph.

    High: 38 °F

    Slight Chance
    Showers then
    Mostly Cloudy

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 21. North wind 5 to 8 mph.

    Low: 21 °F

    Mostly Cloudy

Detailed Forecast

Overnight
A 20 percent chance of snow before 3am. Mostly cloudy, with a low around 23. North wind 6 to 10 mph.
Thursday
Partly sunny, with a high near 30. North wind 5 to 10 mph.
Thursday Night
Mostly cloudy, then gradually becoming mostly clear, with a low around 17. Light north wind.
Friday
Sunny, with a high near 41. Calm wind becoming south 5 to 7 mph in the afternoon.
Friday Night
Partly cloudy, with a low around 26. Southwest wind 3 to 6 mph.
Saturday
Mostly sunny, with a high near 43. Calm wind becoming west around 5 mph.
Saturday Night
A slight chance of freezing rain after midnight. Mostly cloudy, with a low around 28. East northeast wind 3 to 6 mph. Chance of precipitation is 20%.
Sunday
A slight chance of showers before noon. Mostly cloudy, with a high near 38. North wind 6 to 9 mph.
Sunday Night
Mostly cloudy, with a low around 21. North wind 5 to 8 mph.
Monday
Mostly sunny, with a high near 35. North wind around 6 mph becoming light and variable in the afternoon.
Monday Night
Partly cloudy, with a low around 23. Light and variable wind becoming south southwest 5 to 8 mph after midnight.
Tuesday
Mostly sunny, with a high near 45. Southwest wind 8 to 11 mph, with gusts as high as 18 mph.
Tuesday Night
Mostly cloudy, with a low around 32. South southwest wind 8 to 11 mph, with gusts as high as 18 mph.
Wednesday
A chance of showers. Mostly cloudy, with a high near 50. South southwest wind 10 to 13 mph becoming west in the afternoon. Winds could gust as high as 20 mph.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Saint Johns IL
 38.03°N 89.24°W
Last Update:
1:21 am CST Dec 4, 2025
Forecast Valid:
1am CST Dec 4, 2025-6pm CST Dec 10, 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