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

55°F

13°C

Humidity 55%
Wind Speed Vrbl 3 mph
Barometer 29.87 in
Dewpoint 39°F (4°C)
Visibility 10.00 mi
Last update 26 Feb 12:47 pm CST
Extended Forecast for

Saint Johns IL

  • This Afternoon

    This Afternoon: Sunny, with a high near 56. East wind around 5 mph becoming calm.

    High: 56 °F

    Sunny

  • Tonight

    Tonight: Clear, with a low around 35. Light and variable wind.

    Low: 35 °F

    Clear

  • Friday

    Friday: Sunny, with a high near 70. Light south southwest wind becoming southwest 6 to 11 mph in the morning.

    High: 70 °F

    Sunny

  • Friday Night

    Friday Night: Clear, with a low around 41. South southwest wind 6 to 8 mph becoming north after midnight.

    Low: 41 °F

    Clear

  • Saturday

    Saturday: Mostly sunny, with a high near 65. North northeast wind 6 to 8 mph becoming south southwest in the afternoon.

    High: 65 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 33. South southeast wind 8 to 10 mph becoming north in the evening. Winds could gust as high as 18 mph.

    Low: 33 °F

    Partly Cloudy

  • Sunday

    Sunday: A chance of rain and snow showers after noon. Mostly cloudy, with a high near 45. Northeast wind around 11 mph, with gusts as high as 18 mph. Chance of precipitation is 30%.

    High: 45 °F

    Mostly Cloudy
    then Chance
    Rain/Snow

  • Sunday Night

    Sunday Night: Rain and snow showers likely. Cloudy, with a low around 33. East northeast wind around 10 mph.

    Low: 33 °F

    Rain/Snow
    Likely

  • Monday

    Monday: A chance of rain and snow showers before noon. Mostly cloudy, with a high near 44. East northeast wind 7 to 10 mph, with gusts as high as 18 mph.

    High: 44 °F

    Chance
    Rain/Snow
    then Mostly
    Cloudy

Detailed Forecast

This Afternoon
Sunny, with a high near 56. East wind around 5 mph becoming calm.
Tonight
Clear, with a low around 35. Light and variable wind.
Friday
Sunny, with a high near 70. Light south southwest wind becoming southwest 6 to 11 mph in the morning.
Friday Night
Clear, with a low around 41. South southwest wind 6 to 8 mph becoming north after midnight.
Saturday
Mostly sunny, with a high near 65. North northeast wind 6 to 8 mph becoming south southwest in the afternoon.
Saturday Night
Partly cloudy, with a low around 33. South southeast wind 8 to 10 mph becoming north in the evening. Winds could gust as high as 18 mph.
Sunday
A chance of rain and snow showers after noon. Mostly cloudy, with a high near 45. Northeast wind around 11 mph, with gusts as high as 18 mph. Chance of precipitation is 30%.
Sunday Night
Rain and snow showers likely. Cloudy, with a low around 33. East northeast wind around 10 mph.
Monday
A chance of rain and snow showers before noon. Mostly cloudy, with a high near 44. East northeast wind 7 to 10 mph, with gusts as high as 18 mph.
Monday Night
A chance of showers, mainly after midnight. Mostly cloudy, with a low around 32. East wind around 6 mph.
Tuesday
Showers likely. Cloudy, with a high near 50. East wind around 7 mph becoming south in the afternoon.
Tuesday Night
Showers likely. Cloudy, with a low around 40. South wind around 7 mph.
Wednesday
A chance of showers. Cloudy, with a high near 59. South wind 7 to 10 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:
12:21 pm CST Feb 26, 2026
Forecast Valid:
1pm CST Feb 26, 2026-6pm CST Mar 4, 2026
 
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Additional Resources

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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