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

48°F

9°C

Humidity 86%
Wind Speed S 8 mph
Barometer 29.95 in (1014.0 mb)
Dewpoint 44°F (7°C)
Visibility 10.00 mi
Wind Chill44°F (7°C)
Last update 9 Mar 1:52 am CDT
Extended Forecast for

Saint Johns IL

  • Overnight

    Overnight: Clear, with a low around 47. South wind around 8 mph.

    Low: 47 °F

    Clear

  • Monday

    Monday: Mostly sunny, with a high near 73. South southwest wind 8 to 16 mph, with gusts as high as 25 mph.

    High: 73 °F

    Mostly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 62. South southwest wind 9 to 14 mph, with gusts as high as 23 mph.

    Low: 62 °F

    Partly Cloudy

  • Tuesday

    Tuesday: A slight chance of showers between 1pm and 4pm, then a slight chance of showers and thunderstorms after 4pm. Patchy fog between 8am and 10am. Otherwise, partly sunny, with a high near 78. South southwest wind 8 to 15 mph, with gusts as high as 23 mph. Chance of precipitation is 20%.

    High: 78 °F

    Patchy Fog
    then Slight
    Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1am. Low around 61. South southwest wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 80%.

    Low: 61 °F

    Chance
    T-storms then
    Showers

  • Wednesday

    Wednesday: Showers and possibly a thunderstorm. High near 70. South southwest wind 15 to 17 mph becoming northwest in the afternoon. Winds could gust as high as 26 mph. Chance of precipitation is 100%.

    High: 70 °F

    Showers

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 34. Breezy, with a north northwest wind 16 to 21 mph decreasing to 10 to 15 mph after midnight. Winds could gust as high as 29 mph.

    Low: 34 °F

    Mostly Cloudy
    and Breezy
    then Partly
    Cloudy

  • Thursday

    Thursday: Sunny, with a high near 53. North northwest wind around 7 mph becoming south southwest in the afternoon.

    High: 53 °F

    Sunny

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 42. South wind 7 to 15 mph, with gusts as high as 25 mph.

    Low: 42 °F

    Mostly Cloudy

Detailed Forecast

Overnight
Clear, with a low around 47. South wind around 8 mph.
Monday
Mostly sunny, with a high near 73. South southwest wind 8 to 16 mph, with gusts as high as 25 mph.
Monday Night
Partly cloudy, with a low around 62. South southwest wind 9 to 14 mph, with gusts as high as 23 mph.
Tuesday
A slight chance of showers between 1pm and 4pm, then a slight chance of showers and thunderstorms after 4pm. Patchy fog between 8am and 10am. Otherwise, partly sunny, with a high near 78. South southwest wind 8 to 15 mph, with gusts as high as 23 mph. Chance of precipitation is 20%.
Tuesday Night
A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1am. Low around 61. South southwest wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 80%.
Wednesday
Showers and possibly a thunderstorm. High near 70. South southwest wind 15 to 17 mph becoming northwest in the afternoon. Winds could gust as high as 26 mph. Chance of precipitation is 100%.
Wednesday Night
Mostly cloudy, with a low around 34. Breezy, with a north northwest wind 16 to 21 mph decreasing to 10 to 15 mph after midnight. Winds could gust as high as 29 mph.
Thursday
Sunny, with a high near 53. North northwest wind around 7 mph becoming south southwest in the afternoon.
Thursday Night
Mostly cloudy, with a low around 42. South wind 7 to 15 mph, with gusts as high as 25 mph.
Friday
Partly sunny, with a high near 65. Southwest wind 10 to 15 mph becoming west northwest in the afternoon. Winds could gust as high as 24 mph.
Friday Night
Partly cloudy, with a low around 39. North northwest wind around 6 mph becoming east after midnight.
Saturday
Sunny, with a high near 66. East wind 7 to 11 mph becoming south in the afternoon. Winds could gust as high as 20 mph.
Saturday Night
Mostly cloudy, with a low around 50. South wind 10 to 14 mph, with gusts as high as 23 mph.
Sunday
A chance of showers. Partly sunny, with a high near 70. South southwest wind 14 to 18 mph, with gusts as high as 28 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 Mar 9, 2026
Forecast Valid:
2am CDT Mar 9, 2026-6pm CDT Mar 15, 2026
 
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Additional Resources

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Chance of Precipitation