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

16°F

-9°C

Humidity 84%
Wind Speed N 3 mph
Barometer 30.25 in (1025.0 mb)
Dewpoint 12°F (-11°C)
Visibility 10.00 mi
Last update 29 Jan 3:52 am CST
Extended Forecast for

Saint Johns IL

  • Today

    Today: Scattered flurries after noon. Mostly cloudy, with a high near 26. East northeast wind 5 to 7 mph.

    High: 26 °F

    Scattered
    Flurries

  • Tonight

    Tonight: Scattered snow showers, mainly between midnight and 3am. Mostly cloudy, with a low around 10. North northeast wind around 7 mph. Chance of precipitation is 40%.

    Low: 10 °F

    Scattered
    Snow Showers

  • Friday

    Friday: Partly sunny, with a high near 19. Wind chill values as low as zero. North wind 6 to 10 mph.

    High: 19 °F

    Partly Sunny

  • Friday Night

    Friday Night: Mostly cloudy, with a low around 4. Wind chill values as low as -10. North northwest wind around 10 mph, with gusts as high as 18 mph.

    Low: 4 °F

    Mostly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 18. Northwest wind 8 to 13 mph, with gusts as high as 20 mph.

    High: 18 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 1. Northwest wind 3 to 7 mph.

    Low: 1 °F

    Mostly Clear

  • Sunday

    Sunday: Partly sunny, with a high near 26. Light and variable wind becoming south southwest 5 to 7 mph in the morning.

    High: 26 °F

    Partly Sunny

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 17. South southwest wind around 6 mph.

    Low: 17 °F

    Mostly Cloudy

  • Monday

    Monday: Partly sunny, with a high near 34. West southwest wind 6 to 8 mph.

    High: 34 °F

    Partly Sunny

Detailed Forecast

Today
Scattered flurries after noon. Mostly cloudy, with a high near 26. East northeast wind 5 to 7 mph.
Tonight
Scattered snow showers, mainly between midnight and 3am. Mostly cloudy, with a low around 10. North northeast wind around 7 mph. Chance of precipitation is 40%.
Friday
Partly sunny, with a high near 19. Wind chill values as low as zero. North wind 6 to 10 mph.
Friday Night
Mostly cloudy, with a low around 4. Wind chill values as low as -10. North northwest wind around 10 mph, with gusts as high as 18 mph.
Saturday
Mostly sunny, with a high near 18. Northwest wind 8 to 13 mph, with gusts as high as 20 mph.
Saturday Night
Mostly clear, with a low around 1. Northwest wind 3 to 7 mph.
Sunday
Partly sunny, with a high near 26. Light and variable wind becoming south southwest 5 to 7 mph in the morning.
Sunday Night
Mostly cloudy, with a low around 17. South southwest wind around 6 mph.
Monday
Partly sunny, with a high near 34. West southwest wind 6 to 8 mph.
Monday Night
Mostly cloudy, with a low around 23. West southwest wind around 5 mph becoming calm in the evening.
Tuesday
Mostly cloudy, with a high near 36. South wind 3 to 6 mph.
Tuesday Night
A chance of rain showers, snow showers, and freezing rain. Mostly cloudy, with a low around 23. Calm wind becoming north around 6 mph in the evening.
Wednesday
A chance of snow showers. Mostly cloudy, with a high near 35. North northwest wind 5 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:
3:56 am CST Jan 29, 2026
Forecast Valid:
4am CST Jan 29, 2026-6pm CST Feb 4, 2026
 
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Additional Resources

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Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation