National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Hazardous Weather Conditions

Current conditions at

Marion - Williamson County Regional Airport (KMWA)

Lat: 37.77°NLon: 89.01°WElev: 486ft.

Fair

76°F

24°C

Humidity 89%
Wind Speed SE 7 mph
Barometer 30.02 in
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Heat Index76°F (24°C)
Last update 12 Aug 3:55 am CDT
Extended Forecast for

Johnston City IL

  • Overnight

    Overnight: A 20 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 73. Calm wind.

    Low: 73 °F

    Slight Chance
    T-storms

  • Tuesday

    Tuesday: A slight chance of showers and thunderstorms between 1pm and 2pm. Partly sunny, with a high near 93. Calm wind becoming south southwest around 6 mph in the morning. Chance of precipitation is 20%.

    High: 93 °F

    Mostly Cloudy
    then Slight
    Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A 20 percent chance of showers and thunderstorms before 1am. Patchy fog after 4am. Otherwise, mostly cloudy, with a low around 72. Light and variable wind.

    Low: 72 °F

    Slight Chance
    T-storms and
    Patchy Fog

  • Wednesday

    Wednesday: A slight chance of showers, then a chance of showers and thunderstorms after 10am. Patchy fog before 7am. Otherwise, mostly sunny, with a high near 90. Calm wind becoming west northwest around 5 mph in the afternoon. Chance of precipitation is 40%.

    High: 90 °F

    Chance
    T-storms and
    Patchy Fog

  • Wednesday Night

    Wednesday Night: A slight chance of showers and thunderstorms before 10pm, then a slight chance of showers between 10pm and 1am. Partly cloudy, with a low around 70. Calm wind. Chance of precipitation is 20%.

    Low: 70 °F

    Slight Chance
    T-storms then
    Slight Chance
    Showers

  • Thursday

    Thursday: A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 90. Calm wind.

    High: 90 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 71. Calm wind.

    Low: 71 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 95. Light south southwest wind.

    High: 95 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 75. Calm wind.

    Low: 75 °F

    Mostly Clear

Detailed Forecast

Overnight
A 20 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 73. Calm wind.
Tuesday
A slight chance of showers and thunderstorms between 1pm and 2pm. Partly sunny, with a high near 93. Calm wind becoming south southwest around 6 mph in the morning. Chance of precipitation is 20%.
Tuesday Night
A 20 percent chance of showers and thunderstorms before 1am. Patchy fog after 4am. Otherwise, mostly cloudy, with a low around 72. Light and variable wind.
Wednesday
A slight chance of showers, then a chance of showers and thunderstorms after 10am. Patchy fog before 7am. Otherwise, mostly sunny, with a high near 90. Calm wind becoming west northwest around 5 mph in the afternoon. Chance of precipitation is 40%.
Wednesday Night
A slight chance of showers and thunderstorms before 10pm, then a slight chance of showers between 10pm and 1am. Partly cloudy, with a low around 70. Calm wind. Chance of precipitation is 20%.
Thursday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 90. Calm wind.
Thursday Night
Mostly clear, with a low around 71. Calm wind.
Friday
Sunny, with a high near 95. Light south southwest wind.
Friday Night
Mostly clear, with a low around 75. Calm wind.
Saturday
Sunny and hot, with a high near 97. Calm wind becoming south southwest around 5 mph.
Saturday Night
Mostly clear, with a low around 76. Calm wind.
Sunday
Sunny and hot, with a high near 99. Light south wind.
Sunday Night
Partly cloudy, with a low around 74. Light and variable wind.
Monday
Mostly sunny, with a high near 96. Calm wind becoming south southeast around 6 mph in the afternoon.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Johnston City IL
 37.82°N 88.91°W
Last Update:
3:01 am CDT Aug 12, 2025
Forecast Valid:
4am CDT Aug 12, 2025-6pm CDT Aug 18, 2025
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

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