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

77°F

25°C

Humidity 59%
Wind Speed Calm
Barometer 30.00 in
Dewpoint 61°F (16°C)
Visibility 10.00 mi
Heat Index79°F (26°C)
Last update 20 Sep 7:15 pm CDT
Extended Forecast for

Johnston City IL

  • Tonight

    Tonight: A slight chance of showers and thunderstorms before 10pm, then a slight chance of showers and thunderstorms after 3am. Mostly cloudy, with a low around 66. Calm wind. Chance of precipitation is 20%.

    Low: 66 °F

    Slight Chance
    T-storms

  • Sunday

    Sunday: A 40 percent chance of showers and thunderstorms, mainly before 4pm. Mostly cloudy, with a high near 86. Southwest wind 5 to 10 mph.

    High: 86 °F

    Chance
    T-storms

  • Sunday Night

    Sunday Night: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 66. South wind 3 to 6 mph. Chance of precipitation is 60%.

    Low: 66 °F

    Chance
    T-storms then
    Showers
    Likely

  • Monday

    Monday: Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 83. South wind 6 to 10 mph. Chance of precipitation is 70%.

    High: 83 °F

    Showers
    Likely

  • Monday Night

    Monday Night: Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 65. South wind 3 to 6 mph. Chance of precipitation is 70%.

    Low: 65 °F

    Showers
    Likely

  • Tuesday

    Tuesday: A chance of showers and thunderstorms before 7am, then a chance of showers between 7am and 1pm, then showers likely and possibly a thunderstorm after 1pm. Mostly cloudy, with a high near 79. South southwest wind 5 to 7 mph. Chance of precipitation is 60%.

    High: 79 °F

    Showers
    Likely

  • Tuesday Night

    Tuesday Night: Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 65. Calm wind becoming south southeast around 5 mph after midnight. Chance of precipitation is 70%.

    Low: 65 °F

    Showers
    Likely

  • Wednesday

    Wednesday: Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 76. Southeast wind 6 to 9 mph.

    High: 76 °F

    Showers
    Likely

  • Wednesday Night

    Wednesday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 62. East wind 5 to 7 mph becoming north after midnight.

    Low: 62 °F

    Chance
    Showers

Detailed Forecast

Tonight
A slight chance of showers and thunderstorms before 10pm, then a slight chance of showers and thunderstorms after 3am. Mostly cloudy, with a low around 66. Calm wind. Chance of precipitation is 20%.
Sunday
A 40 percent chance of showers and thunderstorms, mainly before 4pm. Mostly cloudy, with a high near 86. Southwest wind 5 to 10 mph.
Sunday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 66. South wind 3 to 6 mph. Chance of precipitation is 60%.
Monday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 83. South wind 6 to 10 mph. Chance of precipitation is 70%.
Monday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 65. South wind 3 to 6 mph. Chance of precipitation is 70%.
Tuesday
A chance of showers and thunderstorms before 7am, then a chance of showers between 7am and 1pm, then showers likely and possibly a thunderstorm after 1pm. Mostly cloudy, with a high near 79. South southwest wind 5 to 7 mph. Chance of precipitation is 60%.
Tuesday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 65. Calm wind becoming south southeast around 5 mph after midnight. Chance of precipitation is 70%.
Wednesday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 76. Southeast wind 6 to 9 mph.
Wednesday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 62. East wind 5 to 7 mph becoming north after midnight.
Thursday
A chance of showers, with thunderstorms also possible after 1pm. Mostly cloudy, with a high near 76. Northwest wind 6 to 10 mph.
Thursday Night
A chance of showers. Mostly cloudy, with a low around 59. North northwest wind 3 to 6 mph.
Friday
A chance of showers. Partly sunny, with a high near 76. North northwest wind 6 to 8 mph.
Friday Night
Partly cloudy, with a low around 59. North northwest wind around 5 mph becoming calm in the evening.
Saturday
Mostly sunny, with a high near 78. North northwest wind 3 to 7 mph.
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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:
6:01 pm CDT Sep 20, 2025
Forecast Valid:
7pm CDT Sep 20, 2025-6pm CDT Sep 27, 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