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.

Overcast

72°F

22°C

Humidity 66%
Wind Speed S 16 G 23 mph
Barometer 30.09 in (1018.4 mb)
Dewpoint 60°F (16°C)
Visibility 10.00 mi
Last update 13 Apr 9:52 am CDT
Extended Forecast for

Saint Johns IL

  • Today

    Today: Mostly sunny, with a high near 81. South southwest wind 10 to 17 mph, with gusts as high as 28 mph.

    High: 81 °F

    Mostly Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 67. South southwest wind around 15 mph, with gusts as high as 30 mph.

    Low: 67 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 86. South southwest wind 13 to 17 mph, with gusts as high as 26 mph.

    High: 86 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: A 20 percent chance of showers after 1am. Partly cloudy, with a low around 69. South southwest wind 10 to 15 mph, with gusts as high as 24 mph.

    Low: 69 °F

    Partly Cloudy
    then Slight
    Chance
    Showers

  • Wednesday

    Wednesday: A chance of showers, with thunderstorms also possible after 1pm. Mostly cloudy, with a high near 83. South southwest wind 10 to 15 mph, with gusts as high as 23 mph. Chance of precipitation is 40%.

    High: 83 °F

    Chance
    Showers then
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 63. South southwest wind 10 to 13 mph, with gusts as high as 21 mph. Chance of precipitation is 70%.

    Low: 63 °F

    Chance
    T-storms then
    Showers
    Likely

  • Thursday

    Thursday: A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 82. South southwest wind 10 to 13 mph, with gusts as high as 20 mph.

    High: 82 °F

    Chance
    T-storms

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 62. South southwest wind around 6 mph.

    Low: 62 °F

    Mostly Clear

  • Friday

    Friday: Mostly sunny, with a high near 86. South wind 6 to 13 mph, with gusts as high as 21 mph.

    High: 86 °F

    Mostly Sunny

Detailed Forecast

Today
Mostly sunny, with a high near 81. South southwest wind 10 to 17 mph, with gusts as high as 28 mph.
Tonight
Partly cloudy, with a low around 67. South southwest wind around 15 mph, with gusts as high as 30 mph.
Tuesday
Mostly sunny, with a high near 86. South southwest wind 13 to 17 mph, with gusts as high as 26 mph.
Tuesday Night
A 20 percent chance of showers after 1am. Partly cloudy, with a low around 69. South southwest wind 10 to 15 mph, with gusts as high as 24 mph.
Wednesday
A chance of showers, with thunderstorms also possible after 1pm. Mostly cloudy, with a high near 83. South southwest wind 10 to 15 mph, with gusts as high as 23 mph. Chance of precipitation is 40%.
Wednesday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 63. South southwest wind 10 to 13 mph, with gusts as high as 21 mph. Chance of precipitation is 70%.
Thursday
A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 82. South southwest wind 10 to 13 mph, with gusts as high as 20 mph.
Thursday Night
Mostly clear, with a low around 62. South southwest wind around 6 mph.
Friday
Mostly sunny, with a high near 86. South wind 6 to 13 mph, with gusts as high as 21 mph.
Friday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 63. South wind around 11 mph, with gusts as high as 21 mph.
Saturday
Showers likely and possibly a thunderstorm. Partly sunny, with a high near 77. Southwest wind 11 to 15 mph, with gusts as high as 22 mph.
Saturday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 45. Northwest wind 8 to 10 mph, with gusts as high as 18 mph.
Sunday
Mostly sunny, with a high near 64. Northwest wind 8 to 10 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:
9:57 am CDT Apr 13, 2026
Forecast Valid:
10am CDT Apr 13, 2026-6pm CDT Apr 19, 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