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.

Partly Cloudy with Haze

25°F

-4°C

Humidity 78%
Wind Speed N 7 mph
Barometer 30.30 in (1026.5 mb)
Dewpoint 19°F (-7°C)
Visibility 6.00 mi
Wind Chill17°F (-8°C)
Last update 4 Feb 4:52 am CST
Extended Forecast for

Saint Johns IL

  • Today

    Today: Mostly cloudy, then gradually becoming sunny, with a high near 31. North wind 6 to 10 mph.

    High: 31 °F

    Decreasing
    Clouds

  • Tonight

    Tonight: Partly cloudy, with a low around 15. North wind 5 to 7 mph becoming calm in the evening.

    Low: 15 °F

    Partly Cloudy

  • Thursday

    Thursday: Mostly cloudy, with a high near 35. Calm wind becoming south southwest 5 to 8 mph in the morning.

    High: 35 °F

    Mostly Cloudy

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 28. South wind 6 to 8 mph becoming west after midnight.

    Low: 28 °F

    Partly Cloudy

  • Friday

    Friday: Mostly sunny, with a high near 49. West wind 7 to 13 mph becoming north northwest in the afternoon. Winds could gust as high as 20 mph.

    High: 49 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 25. North northwest wind 5 to 7 mph.

    Low: 25 °F

    Partly Cloudy

  • Saturday

    Saturday: Sunny, with a high near 40. North northeast wind around 6 mph becoming southeast in the afternoon.

    High: 40 °F

    Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 28. South southeast wind 5 to 7 mph.

    Low: 28 °F

    Partly Cloudy

  • Sunday

    Sunday: Mostly sunny, with a high near 51. South wind 5 to 8 mph becoming north in the afternoon.

    High: 51 °F

    Mostly Sunny

Detailed Forecast

Today
Mostly cloudy, then gradually becoming sunny, with a high near 31. North wind 6 to 10 mph.
Tonight
Partly cloudy, with a low around 15. North wind 5 to 7 mph becoming calm in the evening.
Thursday
Mostly cloudy, with a high near 35. Calm wind becoming south southwest 5 to 8 mph in the morning.
Thursday Night
Partly cloudy, with a low around 28. South wind 6 to 8 mph becoming west after midnight.
Friday
Mostly sunny, with a high near 49. West wind 7 to 13 mph becoming north northwest in the afternoon. Winds could gust as high as 20 mph.
Friday Night
Partly cloudy, with a low around 25. North northwest wind 5 to 7 mph.
Saturday
Sunny, with a high near 40. North northeast wind around 6 mph becoming southeast in the afternoon.
Saturday Night
Partly cloudy, with a low around 28. South southeast wind 5 to 7 mph.
Sunday
Mostly sunny, with a high near 51. South wind 5 to 8 mph becoming north in the afternoon.
Sunday Night
Partly cloudy, with a low around 28. Light northeast wind.
Monday
Mostly sunny, with a high near 50. Calm wind becoming south southwest around 6 mph in the afternoon.
Monday Night
Mostly cloudy, with a low around 36. South wind around 6 mph.
Tuesday
A slight chance of showers. Partly sunny, with a high near 58. South wind 6 to 9 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:
3:16 am CST Feb 4, 2026
Forecast Valid:
5am CST Feb 4, 2026-6pm CST Feb 10, 2026
 
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Additional Resources

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation