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.

Overcast

75°F

24°C

Humidity 98%
Wind Speed SW 8 mph
Barometer 29.92 in
Dewpoint 75°F (24°C)
Visibility 10.00 mi
Last update 27 Jun 3:55 am CDT
Extended Forecast for

Johnston City IL

Flood Watch June 27, 04:04am until June 28, 07:00am
Click here for hazard details and duration
Flood Watch
  •  
    Flood Watch June 27, 04:04am until June 28, 07:00am

    NOW until 7:00am Sun

    Flood Watch

  • Overnight

    Low: 71 °F

    Showers

  • Saturday

    Saturday: Showers and thunderstorms likely, mainly before 2pm. Mostly cloudy, with a high near 85. Southwest wind 6 to 8 mph. Chance of precipitation is 60%.

    High: 85 °F

    Showers
    Likely

  • Saturday Night

    Saturday Night: A chance of showers and thunderstorms before 4am, then a slight chance of showers. Partly cloudy, with a low around 72. Southwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 40%.

    Low: 72 °F

    Chance
    T-storms

  • Sunday

    Sunday: A 10 percent chance of showers before 7am. Sunny, with a high near 93. Heat index values as high as 106. Light south wind becoming south southwest 6 to 11 mph in the morning.

    High: 93 °F

    Slight Chance
    Showers then
    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 75. South wind 5 to 8 mph.

    Low: 75 °F

    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 95. South southwest wind 5 to 9 mph.

    High: 95 °F

    Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 76. South wind 5 to 7 mph becoming calm after midnight.

    Low: 76 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny and hot, with a high near 97. Calm wind becoming south around 6 mph in the morning.

    High: 97 °F

    Hot

Detailed Forecast

Overnight
Showers and possibly a thunderstorm. Low around 71. Southwest wind around 5 mph. Chance of precipitation is 80%.
Saturday
Showers and thunderstorms likely, mainly before 2pm. Mostly cloudy, with a high near 85. Southwest wind 6 to 8 mph. Chance of precipitation is 60%.
Saturday Night
A chance of showers and thunderstorms before 4am, then a slight chance of showers. Partly cloudy, with a low around 72. Southwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 40%.
Sunday
A 10 percent chance of showers before 7am. Sunny, with a high near 93. Heat index values as high as 106. Light south wind becoming south southwest 6 to 11 mph in the morning.
Sunday Night
Mostly clear, with a low around 75. South wind 5 to 8 mph.
Monday
Sunny, with a high near 95. South southwest wind 5 to 9 mph.
Monday Night
Mostly clear, with a low around 76. South wind 5 to 7 mph becoming calm after midnight.
Tuesday
Sunny and hot, with a high near 97. Calm wind becoming south around 6 mph in the morning.
Tuesday Night
Clear, with a low around 76. Light and variable wind.
Wednesday
Sunny and hot, with a high near 97. Light and variable wind.
Wednesday Night
Mostly clear, with a low around 77. Calm wind.
Thursday
Sunny, with a high near 95. Light and variable wind.
Thursday Night
Mostly clear, with a low around 76. Calm wind.
Friday
A slight chance of showers and thunderstorms. Sunny, with a high near 94. Light and variable wind.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Johnston City IL
 37.82°N 88.91°W
Last Update:
1:26 am CDT Jun 27, 2026
Forecast Valid:
4am CDT Jun 27, 2026-6pm CDT Jul 3, 2026
 
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