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.

N/A

Humidity NA
Wind Speed NA
Barometer NA
Dewpoint N/A
Visibility NA
Last update *** Not a current observation ***
Extended Forecast for

Saint Johns IL

  • Overnight

    Overnight: A 40 percent chance of showers, mainly between 1am and 5am. Mostly cloudy, with a low around 37. Northeast wind 3 to 6 mph.

    Low: 37 °F

    Chance
    Showers

  • Thursday

    Thursday: Mostly sunny, with a high near 57. East northeast wind around 6 mph becoming calm in the afternoon.

    High: 57 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 36. Light and variable wind.

    Low: 36 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 66. Light south southwest wind becoming southwest 5 to 10 mph in the morning.

    High: 66 °F

    Sunny

  • Friday Night

    Friday Night: Clear, with a low around 42. South wind 5 to 8 mph becoming northwest after midnight.

    Low: 42 °F

    Clear

  • Saturday

    Saturday: Mostly sunny, with a high near 65. North northwest wind 5 to 9 mph becoming south southeast in the afternoon.

    High: 65 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: A 20 percent chance of showers before midnight. Partly cloudy, with a low around 34. North northeast wind 9 to 11 mph, with gusts as high as 20 mph.

    Low: 34 °F

    Slight Chance
    Showers then
    Mostly Cloudy

  • Sunday

    Sunday: A chance of showers after noon. Cloudy, with a high near 48. East northeast wind around 11 mph, with gusts as high as 18 mph.

    High: 48 °F

    Mostly Cloudy
    then Chance
    Showers

  • Sunday Night

    Sunday Night: Rain likely, possibly mixed with snow showers. Cloudy, with a low around 32. Northeast wind around 10 mph, with gusts as high as 18 mph.

    Low: 32 °F

    Rain/Snow
    Likely

Detailed Forecast

Overnight
A 40 percent chance of showers, mainly between 1am and 5am. Mostly cloudy, with a low around 37. Northeast wind 3 to 6 mph.
Thursday
Mostly sunny, with a high near 57. East northeast wind around 6 mph becoming calm in the afternoon.
Thursday Night
Mostly clear, with a low around 36. Light and variable wind.
Friday
Sunny, with a high near 66. Light south southwest wind becoming southwest 5 to 10 mph in the morning.
Friday Night
Clear, with a low around 42. South wind 5 to 8 mph becoming northwest after midnight.
Saturday
Mostly sunny, with a high near 65. North northwest wind 5 to 9 mph becoming south southeast in the afternoon.
Saturday Night
A 20 percent chance of showers before midnight. Partly cloudy, with a low around 34. North northeast wind 9 to 11 mph, with gusts as high as 20 mph.
Sunday
A chance of showers after noon. Cloudy, with a high near 48. East northeast wind around 11 mph, with gusts as high as 18 mph.
Sunday Night
Rain likely, possibly mixed with snow showers. Cloudy, with a low around 32. Northeast wind around 10 mph, with gusts as high as 18 mph.
Monday
A chance of rain and snow showers before noon, then a slight chance of rain showers. Cloudy, with a high near 43. Northeast wind 9 to 11 mph, with gusts as high as 18 mph.
Monday Night
A chance of showers. Cloudy, with a low around 32. East northeast wind 6 to 8 mph.
Tuesday
A chance of showers. Cloudy, with a high near 48. East wind 6 to 8 mph becoming west in the afternoon.
Tuesday Night
A chance of showers. Cloudy, with a low around 35. North northeast wind around 6 mph.
Wednesday
A chance of showers. Mostly cloudy, with a high near 55. East wind 6 to 8 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:
12:01 am CST Feb 26, 2026
Forecast Valid:
12am CST Feb 26, 2026-6pm CST Mar 4, 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