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

44°F

7°C

Humidity 79%
Wind Speed Calm
Barometer 30.31 in (1026.5 mb)
Dewpoint 38°F (3°C)
Visibility 10.00 mi
Last update 6 Apr 7:52 am CDT
Extended Forecast for

Saint Johns IL

  • Today

    Today: Sunny, with a high near 65. Northwest wind 6 to 10 mph, with gusts as high as 21 mph.

    High: 65 °F

    Sunny

  • Tonight

    Tonight: Increasing clouds, with a low around 41. North northeast wind 6 to 8 mph.

    Low: 41 °F

    Increasing
    Clouds

  • Tuesday

    Tuesday: Partly sunny, with a high near 56. East northeast wind around 10 mph.

    High: 56 °F

    Partly Sunny

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 39. East southeast wind around 7 mph.

    Low: 39 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Partly sunny, with a high near 72. South wind 6 to 11 mph, with gusts as high as 18 mph.

    High: 72 °F

    Partly Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 53. South southeast wind 8 to 10 mph, with gusts as high as 20 mph.

    Low: 53 °F

    Mostly Cloudy

  • Thursday

    Thursday: A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 71. South wind 10 to 13 mph, with gusts as high as 20 mph.

    High: 71 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Thursday Night

    Thursday Night: A chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 57. South wind around 7 mph.

    Low: 57 °F

    Mostly Cloudy
    then Chance
    Showers

  • Friday

    Friday: A chance of showers and thunderstorms. Partly sunny, with a high near 75. South wind 6 to 8 mph.

    High: 75 °F

    Chance
    Showers then
    Chance
    T-storms

Detailed Forecast

Today
Sunny, with a high near 65. Northwest wind 6 to 10 mph, with gusts as high as 21 mph.
Tonight
Increasing clouds, with a low around 41. North northeast wind 6 to 8 mph.
Tuesday
Partly sunny, with a high near 56. East northeast wind around 10 mph.
Tuesday Night
Partly cloudy, with a low around 39. East southeast wind around 7 mph.
Wednesday
Partly sunny, with a high near 72. South wind 6 to 11 mph, with gusts as high as 18 mph.
Wednesday Night
Mostly cloudy, with a low around 53. South southeast wind 8 to 10 mph, with gusts as high as 20 mph.
Thursday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 71. South wind 10 to 13 mph, with gusts as high as 20 mph.
Thursday Night
A chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 57. South wind around 7 mph.
Friday
A chance of showers and thunderstorms. Partly sunny, with a high near 75. South wind 6 to 8 mph.
Friday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 58. Southwest wind around 5 mph becoming east in the evening.
Saturday
A slight chance of showers and thunderstorms. Mostly sunny, with a high near 80. South wind 6 to 8 mph.
Saturday Night
Partly cloudy, with a low around 61. South southeast wind around 7 mph.
Sunday
A slight chance of showers and thunderstorms. Partly sunny, with a high near 81. South wind 8 to 15 mph, with gusts as high as 22 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:
5:31 am CDT Apr 6, 2026
Forecast Valid:
8am CDT Apr 6, 2026-6pm CDT Apr 12, 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