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

37°F

3°C

Humidity 54%
Wind Speed S 5 mph
Barometer 30.10 in (1019.7 mb)
Dewpoint 22°F (-6°C)
Visibility 10.00 mi
Wind Chill33°F (1°C)
Last update 4 Jan 6:52 pm CST
Extended Forecast for

Saint Johns IL

  • Tonight

    Tonight: Mostly clear, with a low around 32. Calm wind becoming south around 6 mph in the evening.

    Low: 32 °F

    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 55. South southwest wind 6 to 10 mph.

    High: 55 °F

    Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 47. South southwest wind 7 to 10 mph, with gusts as high as 20 mph.

    Low: 47 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 64. West southwest wind 6 to 11 mph, with gusts as high as 20 mph.

    High: 64 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 37. Light west northwest wind.

    Low: 37 °F

    Mostly Clear

  • Wednesday

    Wednesday: Mostly sunny, with a high near 60. Calm wind becoming south around 6 mph in the afternoon.

    High: 60 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: A 30 percent chance of showers after midnight. Mostly cloudy, with a low around 47. South southeast wind 5 to 7 mph.

    Low: 47 °F

    Partly Cloudy
    then Chance
    Showers

  • Thursday

    Thursday: Showers likely. Mostly cloudy, with a high near 61. South southwest wind 7 to 10 mph.

    High: 61 °F

    Showers
    Likely

  • Thursday Night

    Thursday Night: Showers likely, mainly before midnight. Mostly cloudy, with a low around 47. South wind around 9 mph.

    Low: 47 °F

    Showers
    Likely

Detailed Forecast

Tonight
Mostly clear, with a low around 32. Calm wind becoming south around 6 mph in the evening.
Monday
Sunny, with a high near 55. South southwest wind 6 to 10 mph.
Monday Night
Partly cloudy, with a low around 47. South southwest wind 7 to 10 mph, with gusts as high as 20 mph.
Tuesday
Mostly sunny, with a high near 64. West southwest wind 6 to 11 mph, with gusts as high as 20 mph.
Tuesday Night
Mostly clear, with a low around 37. Light west northwest wind.
Wednesday
Mostly sunny, with a high near 60. Calm wind becoming south around 6 mph in the afternoon.
Wednesday Night
A 30 percent chance of showers after midnight. Mostly cloudy, with a low around 47. South southeast wind 5 to 7 mph.
Thursday
Showers likely. Mostly cloudy, with a high near 61. South southwest wind 7 to 10 mph.
Thursday Night
Showers likely, mainly before midnight. Mostly cloudy, with a low around 47. South wind around 9 mph.
Friday
A chance of showers. Mostly sunny, with a high near 56. South wind 9 to 11 mph becoming west in the afternoon. Winds could gust as high as 18 mph.
Friday Night
A slight chance of showers. Partly cloudy, with a low around 35. West wind around 9 mph.
Saturday
Mostly sunny, with a high near 47. West wind 8 to 13 mph, with gusts as high as 20 mph.
Saturday Night
Mostly clear, with a low around 26. West northwest wind around 9 mph.
Sunday
Mostly sunny, with a high near 41. West northwest wind 7 to 10 mph.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Saint Johns IL
 38.03°N 89.24°W
Last Update:
7:21 pm CST Jan 4, 2026
Forecast Valid:
7pm CST Jan 4, 2026-6pm CST Jan 11, 2026
 
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Additional Resources

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Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation