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

53°F

12°C

Humidity 52%
Wind Speed Calm
Barometer 30.08 in (1018.7 mb)
Dewpoint 36°F (2°C)
Visibility 10.00 mi
Last update 9 Feb 2:52 pm CST
Extended Forecast for

Saint Johns IL

  • This Afternoon

    This Afternoon: Sunny, with a high near 52. Calm wind.

    High: 52 °F

    Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 39. Light south southeast wind becoming south southwest 5 to 9 mph in the evening.

    Low: 39 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 63. South southwest wind around 9 mph becoming north northwest in the afternoon.

    High: 63 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Mostly cloudy, then gradually becoming mostly clear, with a low around 30. North wind 6 to 8 mph.

    Low: 30 °F

    Decreasing
    Clouds

  • Wednesday

    Wednesday: Sunny, with a high near 49. North wind 3 to 6 mph.

    High: 49 °F

    Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 30. Calm wind.

    Low: 30 °F

    Mostly Cloudy

  • Thursday

    Thursday: Mostly cloudy, with a high near 46. Calm wind becoming east southeast around 6 mph in the morning.

    High: 46 °F

    Mostly Cloudy

  • Thursday Night

    Thursday Night: A slight chance of showers. Mostly cloudy, with a low around 32. East wind 3 to 5 mph.

    Low: 32 °F

    Slight Chance
    Showers

  • Friday

    Friday: Partly sunny, with a high near 47. East wind 5 to 7 mph.

    High: 47 °F

    Partly Sunny

Detailed Forecast

This Afternoon
Sunny, with a high near 52. Calm wind.
Tonight
Partly cloudy, with a low around 39. Light south southeast wind becoming south southwest 5 to 9 mph in the evening.
Tuesday
Mostly sunny, with a high near 63. South southwest wind around 9 mph becoming north northwest in the afternoon.
Tuesday Night
Mostly cloudy, then gradually becoming mostly clear, with a low around 30. North wind 6 to 8 mph.
Wednesday
Sunny, with a high near 49. North wind 3 to 6 mph.
Wednesday Night
Mostly cloudy, with a low around 30. Calm wind.
Thursday
Mostly cloudy, with a high near 46. Calm wind becoming east southeast around 6 mph in the morning.
Thursday Night
A slight chance of showers. Mostly cloudy, with a low around 32. East wind 3 to 5 mph.
Friday
Partly sunny, with a high near 47. East wind 5 to 7 mph.
Friday Night
A chance of showers, mainly after midnight. Mostly cloudy, with a low around 36. East wind 5 to 7 mph.
Saturday
Showers likely. Cloudy, with a high near 49. East wind 7 to 11 mph, with gusts as high as 18 mph.
Saturday Night
Showers. Cloudy, with a low around 39. East wind around 11 mph, with gusts as high as 21 mph.
Sunday
A chance of showers. Partly sunny, with a high near 52. North northwest wind 9 to 14 mph, with gusts as high as 21 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:
1:17 pm CST Feb 9, 2026
Forecast Valid:
3pm CST Feb 9, 2026-6pm CST Feb 15, 2026
 
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Additional Resources

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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