Areas of Dangerous Heat and Severe Thunderstorms

Dangerous heat will build across the Southwest U.S. through the end of the week with daytime highs of 110-115°F. Heat across the southern Plains will briefly ease to near-normal by late week before returning over much of the Plains into next week. Severe thunderstorms are expected across parts of the central and southern High Plains, central Great Lakes, and Ozarks Wednesday. Read More >

Current conditions at

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

Lat: 38.93°NLon: 90.43°WElev: 436ft.

Fair

74°F

23°C

Humidity 85%
Wind Speed E 5 mph
Barometer 29.99 in (1015.0 mb)
Dewpoint 69°F (21°C)
Visibility 10.00 mi
Last update 25 Aug 10:54 pm CDT
Extended Forecast for

Grafton IL

  • Tonight

    Tonight: Mostly cloudy, with a low around 69. Light southeast wind.

    Low: 69 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: A 20 percent chance of showers and thunderstorms after 3pm.  Mostly sunny, with a high near 89. Light and variable wind becoming west 5 to 8 mph in the morning.

    High: 89 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A 30 percent chance of showers and thunderstorms, mainly before 7pm.  Mostly cloudy, then gradually becoming clear, with a low around 65. Northwest wind around 6 mph becoming calm  in the evening.

    Low: 65 °F

    Chance
    T-storms then
    Mostly Clear

  • Thursday

    Thursday: Sunny, with a high near 86. North wind 5 to 8 mph.

    High: 86 °F

    Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 64. North wind 5 to 7 mph becoming calm  in the evening.

    Low: 64 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 86.

    High: 86 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 63.

    Low: 63 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 87.

    High: 87 °F

    Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 67.

    Low: 67 °F

    Partly Cloudy

Detailed Forecast

Tonight
Mostly cloudy, with a low around 69. Light southeast wind.
Wednesday
A 20 percent chance of showers and thunderstorms after 3pm. Mostly sunny, with a high near 89. Light and variable wind becoming west 5 to 8 mph in the morning.
Wednesday Night
A 30 percent chance of showers and thunderstorms, mainly before 7pm. Mostly cloudy, then gradually becoming clear, with a low around 65. Northwest wind around 6 mph becoming calm in the evening.
Thursday
Sunny, with a high near 86. North wind 5 to 8 mph.
Thursday Night
Mostly clear, with a low around 64. North wind 5 to 7 mph becoming calm in the evening.
Friday
Sunny, with a high near 86.
Friday Night
Mostly clear, with a low around 63.
Saturday
Sunny, with a high near 87.
Saturday Night
Partly cloudy, with a low around 67.
Sunday
Mostly sunny, with a high near 92.
Sunday Night
Mostly clear, with a low around 72.
Monday
Mostly sunny, with a high near 93.
Monday Night
A 20 percent chance of showers. Partly cloudy, with a low around 73.
Tuesday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 92.
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ABOUT THIS FORECAST

 
Point Forecast:
Grafton IL
 38.98°N 90.44°W (Elev. 515 ft)
9:36 pm CDT Aug 25, 2026
11pm CDT Aug 25, 2026-6pm CDT Sep 1, 2026
 
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Additional Resources

Radar & Satellite Image

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Hourly Weather Forecast

National Digital Forecast Database