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

Hazardous Weather Conditions

Current conditions at

St. Charles, St. Charles County Smartt Airport (KSET)

Lat: 38.93°NLon: 90.43°WElev: 436ft.

Fog/Mist

79°F

26°C

Humidity 90%
Wind Speed E 5 mph
Barometer 30.03 in (1016.4 mb)
Dewpoint 76°F (24°C)
Visibility 5.00 mi
Heat Index83°F (28°C)
Last update 18 Aug 7:54 am CDT
Extended Forecast for

5 Miles WNW Grafton IL

Heat Advisory August 18, 08:28am until August 18, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 18, 08:28am until August 18, 08:00pm

    NOW until 8:00pm Mon

    Heat Advisory

  • Today

    High: 94 °F

    Sunny

  • Tonight

    Tonight: A 20 percent chance of showers and thunderstorms after 2am. Partly cloudy, with a low around 73. Light and variable wind becoming southeast around 5 mph.

    Low: 73 °F

    Partly Cloudy
    then Slight
    Chance
    T-storms

  • Tuesday

    Tuesday: A 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 91. Light and variable wind becoming west around 5 mph in the morning.

    High: 91 °F

    Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A chance of showers and thunderstorms before 4am, then a slight chance of showers. Partly cloudy, with a low around 74. North wind around 5 mph. Chance of precipitation is 30%.

    Low: 74 °F

    Chance
    T-storms

  • Wednesday

    Wednesday: A slight chance of showers, with thunderstorms also possible after 10am. Mostly sunny, with a high near 85. Northeast wind 6 to 9 mph. Chance of precipitation is 20%.

    High: 85 °F

    Slight Chance
    T-storms

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 66.

    Low: 66 °F

    Mostly Clear

  • Thursday

    Thursday: Sunny, with a high near 83.

    High: 83 °F

    Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 66.

    Low: 66 °F

    Mostly Clear

Detailed Forecast

Today
Sunny, with a high near 94. Heat index values as high as 103. South wind 5 to 7 mph.
Tonight
A 20 percent chance of showers and thunderstorms after 2am. Partly cloudy, with a low around 73. Light and variable wind becoming southeast around 5 mph.
Tuesday
A 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 91. Light and variable wind becoming west around 5 mph in the morning.
Tuesday Night
A chance of showers and thunderstorms before 4am, then a slight chance of showers. Partly cloudy, with a low around 74. North wind around 5 mph. Chance of precipitation is 30%.
Wednesday
A slight chance of showers, with thunderstorms also possible after 10am. Mostly sunny, with a high near 85. Northeast wind 6 to 9 mph. Chance of precipitation is 20%.
Wednesday Night
Mostly clear, with a low around 66.
Thursday
Sunny, with a high near 83.
Thursday Night
Mostly clear, with a low around 66.
Friday
Sunny, with a high near 85.
Friday Night
Mostly clear, with a low around 67.
Saturday
Mostly sunny, with a high near 85.
Saturday Night
Mostly clear, with a low around 62.
Sunday
Sunny, with a high near 79.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
5 Miles WNW Grafton IL
 39°N 90.5°W (Elev. 801 ft)
Last Update:
7:29 am CDT Aug 18, 2025
Forecast Valid:
8am CDT Aug 18, 2025-6pm CDT Aug 24, 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