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

72°F

22°C

Humidity 73%
Wind Speed S 17 G 29 mph
Barometer 29.96 in (1014.2 mb)
Dewpoint 63°F (17°C)
Visibility 10.00 mi
Last update 14 Apr 1:52 am CDT
Extended Forecast for

Saint Johns IL

  • Overnight

    Overnight: Partly cloudy, with a low around 68. South southwest wind around 14 mph, with gusts as high as 23 mph.

    Low: 68 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 86. South southwest wind 11 to 17 mph, with gusts as high as 26 mph.

    High: 86 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: A slight chance of showers before 2am, then a slight chance of showers after 3am. Partly cloudy, with a low around 68. South southwest wind 11 to 15 mph, with gusts as high as 26 mph. Chance of precipitation is 20%.

    Low: 68 °F

    Mostly Clear
    then Slight
    Chance
    Showers

  • Wednesday

    Wednesday: A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 83. South southwest wind 11 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 30%.

    High: 83 °F

    Chance
    Showers

  • Wednesday Night

    Wednesday Night: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 65. South southwest wind 9 to 13 mph, with gusts as high as 22 mph. Chance of precipitation is 70%.

    Low: 65 °F

    Chance
    T-storms then
    Showers
    Likely

  • Thursday

    Thursday: Showers and possibly a thunderstorm. High near 79. South southwest wind 9 to 13 mph, with gusts as high as 18 mph. Chance of precipitation is 80%.

    High: 79 °F

    Showers

  • Thursday Night

    Thursday Night: A 20 percent chance of showers before 1am. Mostly clear, with a low around 59. South wind 5 to 7 mph.

    Low: 59 °F

    Slight Chance
    Showers

  • Friday

    Friday: A slight chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 84. South wind 5 to 11 mph, with gusts as high as 20 mph.

    High: 84 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Friday Night

    Friday Night: A chance of showers and thunderstorms, mainly after 1am. Mostly cloudy, with a low around 62. South wind around 11 mph, with gusts as high as 21 mph.

    Low: 62 °F

    Chance
    T-storms

Detailed Forecast

Overnight
Partly cloudy, with a low around 68. South southwest wind around 14 mph, with gusts as high as 23 mph.
Tuesday
Mostly sunny, with a high near 86. South southwest wind 11 to 17 mph, with gusts as high as 26 mph.
Tuesday Night
A slight chance of showers before 2am, then a slight chance of showers after 3am. Partly cloudy, with a low around 68. South southwest wind 11 to 15 mph, with gusts as high as 26 mph. Chance of precipitation is 20%.
Wednesday
A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 83. South southwest wind 11 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 30%.
Wednesday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 65. South southwest wind 9 to 13 mph, with gusts as high as 22 mph. Chance of precipitation is 70%.
Thursday
Showers and possibly a thunderstorm. High near 79. South southwest wind 9 to 13 mph, with gusts as high as 18 mph. Chance of precipitation is 80%.
Thursday Night
A 20 percent chance of showers before 1am. Mostly clear, with a low around 59. South wind 5 to 7 mph.
Friday
A slight chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 84. South wind 5 to 11 mph, with gusts as high as 20 mph.
Friday Night
A chance of showers and thunderstorms, mainly after 1am. Mostly cloudy, with a low around 62. South wind around 11 mph, with gusts as high as 21 mph.
Saturday
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Partly sunny, with a high near 74. South southwest wind 13 to 16 mph becoming west in the afternoon. Winds could gust as high as 24 mph.
Saturday Night
A slight chance of showers and thunderstorms. Partly cloudy, with a low around 42. West northwest wind 7 to 11 mph, with gusts as high as 20 mph.
Sunday
Sunny, with a high near 66. West northwest wind 7 to 11 mph, with gusts as high as 18 mph.
Sunday Night
Mostly clear, with a low around 41. Northwest wind 5 to 8 mph becoming light and variable in the evening.
Monday
Sunny, with a high near 69. East southeast wind 5 to 8 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:
1:26 am CDT Apr 14, 2026
Forecast Valid:
2am CDT Apr 14, 2026-6pm CDT Apr 20, 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