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

45°F

7°C

Humidity 68%
Wind Speed E 6 mph
Barometer 30.29 in (1025.8 mb)
Dewpoint 35°F (2°C)
Visibility 10.00 mi
Wind Chill42°F (6°C)
Last update 8 Apr 12:52 am CDT
Extended Forecast for

Saint Johns IL

  • Overnight

    Overnight: Partly cloudy, with a steady temperature around 44. East southeast wind around 6 mph.

    Low: 44 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 73. South wind 6 to 10 mph, with gusts as high as 18 mph.

    High: 73 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 53. South wind around 9 mph.

    Low: 53 °F

    Mostly Clear

  • Thursday

    Thursday: Sunny, with a high near 77. South southwest wind 9 to 13 mph, with gusts as high as 20 mph.

    High: 77 °F

    Sunny

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 56. South wind 6 to 8 mph.

    Low: 56 °F

    Partly Cloudy

  • Friday

    Friday: A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 77. South southwest wind 8 to 10 mph, with gusts as high as 18 mph. Chance of precipitation is 50%.

    High: 77 °F

    Slight Chance
    Showers then
    Chance
    T-storms

  • Friday Night

    Friday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 56. North northwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 40%.

    Low: 56 °F

    Chance
    T-storms then
    Chance
    Showers

  • Saturday

    Saturday: A slight chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 76. East northeast wind around 6 mph becoming southeast in the afternoon.

    High: 76 °F

    Slight Chance
    Showers then
    Slight Chance
    T-storms

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 59. East southeast wind around 6 mph.

    Low: 59 °F

    Partly Cloudy

Detailed Forecast

Overnight
Partly cloudy, with a steady temperature around 44. East southeast wind around 6 mph.
Wednesday
Mostly sunny, with a high near 73. South wind 6 to 10 mph, with gusts as high as 18 mph.
Wednesday Night
Mostly clear, with a low around 53. South wind around 9 mph.
Thursday
Sunny, with a high near 77. South southwest wind 9 to 13 mph, with gusts as high as 20 mph.
Thursday Night
Partly cloudy, with a low around 56. South wind 6 to 8 mph.
Friday
A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 77. South southwest wind 8 to 10 mph, with gusts as high as 18 mph. Chance of precipitation is 50%.
Friday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 56. North northwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 40%.
Saturday
A slight chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 76. East northeast wind around 6 mph becoming southeast in the afternoon.
Saturday Night
Partly cloudy, with a low around 59. East southeast wind around 6 mph.
Sunday
Partly sunny, with a high near 81. South wind 7 to 15 mph, with gusts as high as 23 mph.
Sunday Night
A chance of showers. Mostly cloudy, with a low around 65. South wind 11 to 15 mph, with gusts as high as 24 mph.
Monday
A chance of showers and thunderstorms. Mostly cloudy, with a high near 80. Breezy, with a south southwest wind 15 to 20 mph, with gusts as high as 29 mph.
Monday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 65. South southwest wind around 16 mph, with gusts as high as 26 mph.
Tuesday
A chance of showers and thunderstorms. Partly sunny, with a high near 80. South southwest wind 14 to 16 mph, with gusts as high as 25 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:
1:21 am CDT Apr 8, 2026
Forecast Valid:
1am CDT Apr 8, 2026-6pm CDT Apr 14, 2026
 
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Additional Resources

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Hourly Weather Forecast

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation