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

74°F

23°C

Humidity 37%
Wind Speed S 14 G 21 mph
Barometer 30.01 in (1016.2 mb)
Dewpoint 46°F (8°C)
Visibility 10.00 mi
Last update 25 Mar 1:52 pm CDT
Extended Forecast for

Saint Johns IL

  • This Afternoon

    This Afternoon: Mostly sunny, with a high near 75. South southwest wind around 11 mph, with gusts as high as 18 mph.

    High: 75 °F

    Mostly Sunny

  • Tonight

    Tonight: Mostly cloudy, then gradually becoming clear, with a low around 62. South wind 9 to 13 mph, with gusts as high as 22 mph.

    Low: 62 °F

    Decreasing
    Clouds

  • Thursday

    Thursday: Sunny, with a high near 85. South southwest wind 11 to 17 mph, with gusts as high as 26 mph.

    High: 85 °F

    Sunny

  • Thursday Night

    Thursday Night: Showers likely and possibly a thunderstorm after 1am. Partly cloudy, with a low around 45. South southwest wind 11 to 16 mph becoming north after midnight. Winds could gust as high as 28 mph. Chance of precipitation is 70%.

    Low: 45 °F

    Partly Cloudy
    then Showers
    Likely

  • Friday

    Friday: Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 54. North wind around 16 mph, with gusts as high as 25 mph. Chance of precipitation is 60%.

    High: 54 °F

    Showers
    Likely

  • Friday Night

    Friday Night: Mostly clear, with a low around 32. North wind 6 to 14 mph, with gusts as high as 22 mph.

    Low: 32 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 56. North northeast wind around 6 mph becoming east in the afternoon.

    High: 56 °F

    Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 38. East southeast wind 3 to 6 mph.

    Low: 38 °F

    Partly Cloudy

  • Sunday

    Sunday: Partly sunny, with a high near 64. South wind 6 to 11 mph, with gusts as high as 20 mph.

    High: 64 °F

    Partly Sunny

Detailed Forecast

This Afternoon
Mostly sunny, with a high near 75. South southwest wind around 11 mph, with gusts as high as 18 mph.
Tonight
Mostly cloudy, then gradually becoming clear, with a low around 62. South wind 9 to 13 mph, with gusts as high as 22 mph.
Thursday
Sunny, with a high near 85. South southwest wind 11 to 17 mph, with gusts as high as 26 mph.
Thursday Night
Showers likely and possibly a thunderstorm after 1am. Partly cloudy, with a low around 45. South southwest wind 11 to 16 mph becoming north after midnight. Winds could gust as high as 28 mph. Chance of precipitation is 70%.
Friday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 54. North wind around 16 mph, with gusts as high as 25 mph. Chance of precipitation is 60%.
Friday Night
Mostly clear, with a low around 32. North wind 6 to 14 mph, with gusts as high as 22 mph.
Saturday
Sunny, with a high near 56. North northeast wind around 6 mph becoming east in the afternoon.
Saturday Night
Partly cloudy, with a low around 38. East southeast wind 3 to 6 mph.
Sunday
Partly sunny, with a high near 64. South wind 6 to 11 mph, with gusts as high as 20 mph.
Sunday Night
Mostly cloudy, with a low around 53. South southwest wind 9 to 11 mph, with gusts as high as 21 mph.
Monday
A slight chance of showers and thunderstorms. Mostly sunny, with a high near 76. South southwest wind 11 to 14 mph, with gusts as high as 22 mph.
Monday Night
A slight chance of showers. Partly cloudy, with a low around 60. South southwest wind around 11 mph, with gusts as high as 21 mph.
Tuesday
A chance of showers and thunderstorms. Partly sunny, with a high near 78. South southwest wind 11 to 15 mph, with gusts as high as 23 mph.
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ABOUT THIS FORECAST

 
Point Forecast:
Saint Johns IL
 38.03°N 89.24°W
Last Update:
1:26 pm CDT Mar 25, 2026
Forecast Valid:
2pm CDT Mar 25, 2026-6pm CDT Mar 31, 2026
 
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Additional Resources

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Chance of Precipitation