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.

Fog/Mist

70°F

21°C

Humidity 100%
Wind Speed NE 1 mph
Barometer 30.07 in
Dewpoint 70°F (21°C)
Visibility 3.00 mi
Last update 15 Oct 2:15 am CDT
Extended Forecast for

Johnston City IL

Dense Fog Advisory until October 15, 08:00am
Click here for hazard details and duration
Dense Fog Advisory
  •  
    Dense Fog Advisory until October 15, 08:00am

    NOW until 8:00am Thu

    Dense Fog Advisory

  • Overnight

    Low: 70 °F

    Slight Chance
    T-storms and
    Areas Dense
    Fog

  • Thursday

    Thursday: A 50 percent chance of showers and thunderstorms. Patchy dense fog before 8am. Otherwise, partly sunny, with a high near 88. Light and variable wind becoming southwest 9 to 14 mph in the morning. Winds could gust as high as 21 mph.

    High: 88 °F

    Chance
    T-storms and
    Patchy Dense
    Fog

  • Thursday Night

    Thursday Night: Showers and thunderstorms likely before 4am, then a chance of showers between 4am and 5am. Increasing clouds, with a low around 50. South southwest wind 9 to 18 mph becoming northwest after midnight. Winds could gust as high as 26 mph. Chance of precipitation is 60%.

    Low: 50 °F

    Showers
    Likely

  • Friday

    Friday: A 30 percent chance of showers before 7am. Cloudy, then gradually becoming mostly sunny, with a high near 59. Breezy, with a northwest wind 17 to 21 mph, with gusts as high as 29 mph.

    High: 59 °F

    Breezy.
    Chance
    Showers then
    Partly Sunny

  • Friday Night

    Friday Night: Mostly cloudy, with a low around 42. North wind 13 to 17 mph, with gusts as high as 24 mph.

    Low: 42 °F

    Mostly Cloudy

  • Saturday

    Saturday: Sunny, with a high near 61. North northeast wind 9 to 11 mph.

    High: 61 °F

    Sunny

  • Saturday Night

    Saturday Night: Clear, with a low around 37. Calm wind.

    Low: 37 °F

    Clear

  • Sunday

    Sunday: Sunny, with a high near 67. Calm wind becoming south southeast around 6 mph in the morning.

    High: 67 °F

    Sunny

Detailed Forecast

Overnight
A 20 percent chance of showers and thunderstorms. Areas of dense fog. Otherwise, mostly cloudy, with a steady temperature around 70. Calm wind.
Thursday
A 50 percent chance of showers and thunderstorms. Patchy dense fog before 8am. Otherwise, partly sunny, with a high near 88. Light and variable wind becoming southwest 9 to 14 mph in the morning. Winds could gust as high as 21 mph.
Thursday Night
Showers and thunderstorms likely before 4am, then a chance of showers between 4am and 5am. Increasing clouds, with a low around 50. South southwest wind 9 to 18 mph becoming northwest after midnight. Winds could gust as high as 26 mph. Chance of precipitation is 60%.
Friday
A 30 percent chance of showers before 7am. Cloudy, then gradually becoming mostly sunny, with a high near 59. Breezy, with a northwest wind 17 to 21 mph, with gusts as high as 29 mph.
Friday Night
Mostly cloudy, with a low around 42. North wind 13 to 17 mph, with gusts as high as 24 mph.
Saturday
Sunny, with a high near 61. North northeast wind 9 to 11 mph.
Saturday Night
Clear, with a low around 37. Calm wind.
Sunday
Sunny, with a high near 67. Calm wind becoming south southeast around 6 mph in the morning.
Sunday Night
Mostly clear, with a low around 40. Calm wind.
Monday
Sunny, with a high near 71. Calm wind becoming south around 6 mph in the afternoon.
Monday Night
Partly cloudy, with a low around 44. Calm wind.
Tuesday
Mostly sunny, with a high near 73. Light and variable wind.
Tuesday Night
Mostly clear, with a low around 45. Calm wind.
Wednesday
Sunny, with a high near 77. Calm wind becoming southeast around 5 mph in the afternoon.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Johnston City IL
 37.82°N 88.91°W
Last Update:
1:26 am CDT Oct 15, 2026
Forecast Valid:
2am CDT Oct 15, 2026-6pm CDT Oct 21, 2026
 
Forecast Discussion
 
Get as KML Get as XML

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