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

83°F

28°C

Humidity 48%
Wind Speed S 13 mph
Barometer 30.25 in (1023.8 mb)
Dewpoint 61°F (16°C)
Visibility 10.00 mi
Heat Index84°F (29°C)
Last update 3 Oct 12:52 pm CDT
Extended Forecast for

Saint Johns IL

  • This Afternoon

    This Afternoon: A slight chance of sprinkles after 3pm. Sunny, with a high near 89. South southwest wind around 6 mph.

    High: 89 °F

    Slight Chance
    Sprinkles

  • Tonight

    Tonight: A slight chance of sprinkles before 9pm. Mostly clear, with a low around 60. Light south wind.

    Low: 60 °F

    Slight Chance
    Sprinkles

  • Saturday

    Saturday: Sunny, with a high near 87. Calm wind becoming south southeast 5 to 9 mph in the morning.

    High: 87 °F

    Sunny

  • Saturday Night

    Saturday Night: Clear, with a low around 58. South southeast wind 3 to 6 mph.

    Low: 58 °F

    Clear

  • Sunday

    Sunday: Sunny, with a high near 87. South wind 5 to 13 mph.

    High: 87 °F

    Sunny

  • Sunday Night

    Sunday Night: Clear, with a low around 62. South southeast wind 3 to 6 mph.

    Low: 62 °F

    Clear

  • Monday

    Monday: A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 88. South southeast wind 3 to 6 mph.

    High: 88 °F

    Mostly Sunny
    then Slight
    Chance
    Showers

  • Monday Night

    Monday Night: A slight chance of showers after 1am. Partly cloudy, with a low around 63. East southeast wind around 5 mph becoming calm in the evening.

    Low: 63 °F

    Partly Cloudy
    then Slight
    Chance
    Showers

  • Tuesday

    Tuesday: A chance of showers, with thunderstorms also possible after 1pm. Mostly sunny, with a high near 85. Calm wind becoming north northwest around 6 mph in the morning.

    High: 85 °F

    Chance
    Showers then
    Chance
    T-storms

Detailed Forecast

This Afternoon
A slight chance of sprinkles after 3pm. Sunny, with a high near 89. South southwest wind around 6 mph.
Tonight
A slight chance of sprinkles before 9pm. Mostly clear, with a low around 60. Light south wind.
Saturday
Sunny, with a high near 87. Calm wind becoming south southeast 5 to 9 mph in the morning.
Saturday Night
Clear, with a low around 58. South southeast wind 3 to 6 mph.
Sunday
Sunny, with a high near 87. South wind 5 to 13 mph.
Sunday Night
Clear, with a low around 62. South southeast wind 3 to 6 mph.
Monday
A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 88. South southeast wind 3 to 6 mph.
Monday Night
A slight chance of showers after 1am. Partly cloudy, with a low around 63. East southeast wind around 5 mph becoming calm in the evening.
Tuesday
A chance of showers, with thunderstorms also possible after 1pm. Mostly sunny, with a high near 85. Calm wind becoming north northwest around 6 mph in the morning.
Tuesday Night
A slight chance of showers and thunderstorms. Mostly cloudy, with a low around 59. North northeast wind 5 to 8 mph.
Wednesday
Mostly sunny, with a high near 76. North northeast wind 9 to 11 mph.
Wednesday Night
Mostly clear, with a low around 51. Northeast wind 6 to 8 mph.
Thursday
Sunny, with a high near 75. East northeast wind 6 to 8 mph.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Saint Johns IL
 38.03°N 89.24°W
Last Update:
12:46 pm CDT Oct 3, 2025
Forecast Valid:
1pm CDT Oct 3, 2025-6pm CDT Oct 9, 2025
 
Forecast Discussion
 
Get as KML Get as XML

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