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.

Light Rain

55°F

13°C

Humidity 83%
Wind Speed N 10 mph
Barometer 30.13 in (1019.8 mb)
Dewpoint 50°F (10°C)
Visibility 9.00 mi
Wind Chill52°F (11°C)
Last update 16 Oct 5:52 am CDT
Extended Forecast for

Saint Johns IL

  • Today

    Today: Mostly cloudy, with a high near 55. Breezy, with a northwest wind 11 to 20 mph, with gusts as high as 29 mph.

    High: 55 °F

    Mostly Cloudy
    then Mostly
    Cloudy and
    Breezy

  • Tonight

    Tonight: Partly cloudy, with a low around 39. North wind 11 to 17 mph, with gusts as high as 22 mph.

    Low: 39 °F

    Partly Cloudy

  • Saturday

    Saturday: Sunny, with a high near 61. North northeast wind 7 to 9 mph.

    High: 61 °F

    Sunny

  • Saturday Night

    Saturday Night: Patchy frost after 4am. Otherwise, clear, with a low around 34. Calm wind.

    Low: 34 °F

    Clear then
    Patchy Frost

  • Sunday

    Sunday: Areas of frost before 9am. Otherwise, sunny, with a high near 66. Calm wind becoming southeast around 5 mph in the morning.

    High: 66 °F

    Areas Frost
    then Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 38. Calm wind.

    Low: 38 °F

    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 71. Calm wind becoming south around 5 mph in the afternoon.

    High: 71 °F

    Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 41. Calm wind.

    Low: 41 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny, with a high near 75. Light and variable wind.

    High: 75 °F

    Sunny

Detailed Forecast

Today
Mostly cloudy, with a high near 55. Breezy, with a northwest wind 11 to 20 mph, with gusts as high as 29 mph.
Tonight
Partly cloudy, with a low around 39. North wind 11 to 17 mph, with gusts as high as 22 mph.
Saturday
Sunny, with a high near 61. North northeast wind 7 to 9 mph.
Saturday Night
Patchy frost after 4am. Otherwise, clear, with a low around 34. Calm wind.
Sunday
Areas of frost before 9am. Otherwise, sunny, with a high near 66. Calm wind becoming southeast around 5 mph in the morning.
Sunday Night
Mostly clear, with a low around 38. Calm wind.
Monday
Sunny, with a high near 71. Calm wind becoming south around 5 mph in the afternoon.
Monday Night
Mostly clear, with a low around 41. Calm wind.
Tuesday
Sunny, with a high near 75. Light and variable wind.
Tuesday Night
Mostly clear, with a low around 44. Calm wind.
Wednesday
Sunny, with a high near 77. Light and variable wind.
Wednesday Night
Mostly clear, with a low around 46. Calm wind.
Thursday
Sunny, with a high near 80. Calm wind becoming south around 5 mph in the afternoon.
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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:
4:31 am CDT Oct 16, 2026
Forecast Valid:
6am CDT Oct 16, 2026-6pm CDT Oct 22, 2026
 
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Additional Resources

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Chance of Precipitation