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.

Overcast

21°F

-6°C

Humidity 85%
Wind Speed NW 5 mph
Barometer 30.14 in (1021.1 mb)
Dewpoint 17°F (-8°C)
Visibility 8.00 mi
Wind Chill14°F (-10°C)
Last update 5 Dec 4:52 am CST
Extended Forecast for

Saint Johns IL

  • Today

    Today: Sunny, with a high near 40. Calm wind becoming south 5 to 8 mph in the morning.

    High: 40 °F

    Sunny

  • Tonight

    Tonight: Increasing clouds, with a low around 27. South southwest wind 3 to 7 mph.

    Low: 27 °F

    Increasing
    Clouds

  • Saturday

    Saturday: Cloudy, then gradually becoming mostly sunny, with a high near 42. West wind around 5 mph becoming calm in the afternoon.

    High: 42 °F

    Decreasing
    Clouds

  • Saturday Night

    Saturday Night: A 30 percent chance of showers after midnight. Mostly cloudy, with a low around 31. Calm wind becoming southeast around 5 mph after midnight.

    Low: 31 °F

    Mostly Cloudy
    then Chance
    Showers

  • Sunday

    Sunday: A 20 percent chance of showers before noon. Mostly cloudy, with a high near 43. Southeast wind 5 to 11 mph becoming northwest in the afternoon.

    High: 43 °F

    Slight Chance
    Showers then
    Mostly Cloudy

  • Sunday Night

    Sunday Night: A slight chance of rain and snow showers before 9pm, then a slight chance of snow showers between 9pm and midnight. Mostly cloudy, with a low around 19. North wind 5 to 11 mph. Chance of precipitation is 20%.

    Low: 19 °F

    Slight Chance
    Rain/Snow
    then Mostly
    Cloudy

  • Monday

    Monday: Mostly sunny, with a high near 35. North wind around 5 mph becoming calm in the morning.

    High: 35 °F

    Mostly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 24. Light south wind becoming south southwest 5 to 10 mph in the evening.

    Low: 24 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 47. South southwest wind 10 to 13 mph, with gusts as high as 18 mph.

    High: 47 °F

    Mostly Sunny

Detailed Forecast

Today
Sunny, with a high near 40. Calm wind becoming south 5 to 8 mph in the morning.
Tonight
Increasing clouds, with a low around 27. South southwest wind 3 to 7 mph.
Saturday
Cloudy, then gradually becoming mostly sunny, with a high near 42. West wind around 5 mph becoming calm in the afternoon.
Saturday Night
A 30 percent chance of showers after midnight. Mostly cloudy, with a low around 31. Calm wind becoming southeast around 5 mph after midnight.
Sunday
A 20 percent chance of showers before noon. Mostly cloudy, with a high near 43. Southeast wind 5 to 11 mph becoming northwest in the afternoon.
Sunday Night
A slight chance of rain and snow showers before 9pm, then a slight chance of snow showers between 9pm and midnight. Mostly cloudy, with a low around 19. North wind 5 to 11 mph. Chance of precipitation is 20%.
Monday
Mostly sunny, with a high near 35. North wind around 5 mph becoming calm in the morning.
Monday Night
Partly cloudy, with a low around 24. Light south wind becoming south southwest 5 to 10 mph in the evening.
Tuesday
Mostly sunny, with a high near 47. South southwest wind 10 to 13 mph, with gusts as high as 18 mph.
Tuesday Night
Mostly cloudy, with a low around 36. South southwest wind 10 to 14 mph, with gusts as high as 21 mph.
Wednesday
A chance of showers. Mostly cloudy, with a high near 50. South southwest wind 11 to 15 mph becoming west northwest in the afternoon. Winds could gust as high as 22 mph.
Wednesday Night
A slight chance of showers. Mostly cloudy, with a low around 23. Northwest wind 7 to 10 mph.
Thursday
Mostly cloudy, with a high near 35. Northwest wind 7 to 10 mph becoming south southwest in the afternoon.
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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:
4:16 am CST Dec 5, 2025
Forecast Valid:
5am CST Dec 5, 2025-6pm CST Dec 11, 2025
 
Forecast Discussion
 
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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