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

73°F

23°C

Humidity 55%
Wind Speed S 16 mph
Barometer 29.97 in (1014.7 mb)
Dewpoint 56°F (13°C)
Visibility 10.00 mi
Last update 30 Mar 8:52 pm CDT
Extended Forecast for

Saint Johns IL

  • Tonight

    Tonight: Mostly clear, with a low around 64. South southwest wind 13 to 15 mph, with gusts as high as 25 mph.

    Low: 64 °F

    Mostly Clear

  • Tuesday

    Tuesday: Mostly sunny, with a high near 82. Breezy, with a south southwest wind 14 to 21 mph, with gusts as high as 30 mph.

    High: 82 °F

    Mostly Sunny
    and Breezy

  • Tuesday Night

    Tuesday Night: A 30 percent chance of showers after 1am. Partly cloudy, with a low around 63. South southwest wind 9 to 14 mph, with gusts as high as 23 mph.

    Low: 63 °F

    Partly Cloudy
    then Chance
    Showers

  • Wednesday

    Wednesday: Showers likely, mainly after 1pm. Mostly cloudy, with a high near 79. South southwest wind 7 to 11 mph. Chance of precipitation is 60%.

    High: 79 °F

    Showers
    Likely

  • Wednesday Night

    Wednesday Night: A 40 percent chance of showers. Mostly cloudy, with a low around 65. South southeast wind 9 to 14 mph, with gusts as high as 23 mph.

    Low: 65 °F

    Chance
    Showers

  • Thursday

    Thursday: A chance of showers before 10am, then a chance of showers and thunderstorms between 10am and 1pm, then showers likely and possibly a thunderstorm after 1pm. Mostly cloudy, with a high near 79. Breezy, with a south wind 14 to 20 mph, with gusts as high as 29 mph. Chance of precipitation is 70%.

    High: 79 °F

    Breezy.
    Chance
    Showers then
    Showers
    Likely

  • Thursday Night

    Thursday Night: Showers and possibly a thunderstorm. Low around 63. South wind 14 to 18 mph, with gusts as high as 28 mph. Chance of precipitation is 90%.

    Low: 63 °F

    Showers

  • Friday

    Friday: Showers likely, with thunderstorms also possible after 1pm. Mostly cloudy, with a high near 79. South wind 10 to 14 mph, with gusts as high as 21 mph.

    High: 79 °F

    Showers
    Likely

  • Friday Night

    Friday Night: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 61. South wind 11 to 13 mph, with gusts as high as 21 mph.

    Low: 61 °F

    Showers
    Likely

Detailed Forecast

Tonight
Mostly clear, with a low around 64. South southwest wind 13 to 15 mph, with gusts as high as 25 mph.
Tuesday
Mostly sunny, with a high near 82. Breezy, with a south southwest wind 14 to 21 mph, with gusts as high as 30 mph.
Tuesday Night
A 30 percent chance of showers after 1am. Partly cloudy, with a low around 63. South southwest wind 9 to 14 mph, with gusts as high as 23 mph.
Wednesday
Showers likely, mainly after 1pm. Mostly cloudy, with a high near 79. South southwest wind 7 to 11 mph. Chance of precipitation is 60%.
Wednesday Night
A 40 percent chance of showers. Mostly cloudy, with a low around 65. South southeast wind 9 to 14 mph, with gusts as high as 23 mph.
Thursday
A chance of showers before 10am, then a chance of showers and thunderstorms between 10am and 1pm, then showers likely and possibly a thunderstorm after 1pm. Mostly cloudy, with a high near 79. Breezy, with a south wind 14 to 20 mph, with gusts as high as 29 mph. Chance of precipitation is 70%.
Thursday Night
Showers and possibly a thunderstorm. Low around 63. South wind 14 to 18 mph, with gusts as high as 28 mph. Chance of precipitation is 90%.
Friday
Showers likely, with thunderstorms also possible after 1pm. Mostly cloudy, with a high near 79. South wind 10 to 14 mph, with gusts as high as 21 mph.
Friday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 61. South wind 11 to 13 mph, with gusts as high as 21 mph.
Saturday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 72. South wind 13 to 17 mph, with gusts as high as 24 mph.
Saturday Night
A chance of showers. Mostly cloudy, with a low around 42. West northwest wind around 14 mph, with gusts as high as 21 mph.
Sunday
A chance of showers. Mostly sunny, with a high near 59. West northwest wind around 14 mph, with gusts as high as 21 mph.
Sunday Night
Mostly clear, with a low around 38. North wind 7 to 10 mph.
Monday
Sunny, with a high near 63. North wind 7 to 9 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:
7:21 pm CDT Mar 30, 2026
Forecast Valid:
9pm CDT Mar 30, 2026-6pm CDT Apr 6, 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