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

Severe Thunderstorms in the Midwest and Arizona; Heat Continues in the Southeast and Southwest

Thunderstorms, some severe, may lead to scattered instances of flash flooding across the Midwest and Ohio Valley and southern Arizona. The threat will shift to the Mid-Atlantic coast on Thursday. Dangerous heat persists in the South and Southeast while building into the Southwest. Overnight lows will be so warm that little-to-no relief from the scorching daytime highs will be available. Read More >

Current conditions at

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

Lat: 38.93°NLon: 90.43°WElev: 436ft.

Mostly Cloudy

74°F

23°C

Humidity 94%
Wind Speed NW 3 mph
Barometer 29.91 in (1012.4 mb)
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Last update 20 Aug 12:54 am CDT
Extended Forecast for

3 Miles SSE St. Charles County Smartt Airport MO

  • Overnight

    Overnight: Patchy fog after 5am. Otherwise, partly cloudy, with a low around 70. Light and variable wind.

    Low: 70 °F

    Patchy Fog

  • Thursday

    Thursday: Patchy fog before 8am. Otherwise, partly sunny, with a high near 84. Northeast wind 3 to 7 mph.

    High: 84 °F

    Patchy Fog
    then Mostly
    Sunny

  • Thursday Night

    Thursday Night: Patchy fog after 5am. Otherwise, mostly clear, with a low around 67. Northeast wind around 6 mph becoming calm in the evening.

    Low: 67 °F

    Mostly Clear
    then Patchy
    Fog

  • Friday

    Friday: Patchy fog before 8am. Otherwise, sunny, with a high near 88. Calm wind becoming west around 5 mph in the afternoon.

    High: 88 °F

    Patchy Fog
    then Sunny

  • Friday Night

    Friday Night: A 20 percent chance of showers and thunderstorms after 1am. Mostly clear, with a low around 68. Light southwest wind.

    Low: 68 °F

    Mostly Clear
    then Slight
    Chance
    T-storms

  • Saturday

    Saturday: A 20 percent chance of showers before 1pm. Sunny, with a high near 87.

    High: 87 °F

    Slight Chance
    Showers

  • Saturday Night

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

    Low: 66 °F

    Mostly Clear

  • Sunday

    Sunday: Mostly sunny, with a high near 84.

    High: 84 °F

    Mostly Sunny

  • Sunday Night

    Sunday Night: A slight chance of showers and thunderstorms. Mostly cloudy, with a low around 66. Chance of precipitation is 20%.

    Low: 66 °F

    Slight Chance
    T-storms

Detailed Forecast

Overnight
Patchy fog after 5am. Otherwise, partly cloudy, with a low around 70. Light and variable wind.
Thursday
Patchy fog before 8am. Otherwise, partly sunny, with a high near 84. Northeast wind 3 to 7 mph.
Thursday Night
Patchy fog after 5am. Otherwise, mostly clear, with a low around 67. Northeast wind around 6 mph becoming calm in the evening.
Friday
Patchy fog before 8am. Otherwise, sunny, with a high near 88. Calm wind becoming west around 5 mph in the afternoon.
Friday Night
A 20 percent chance of showers and thunderstorms after 1am. Mostly clear, with a low around 68. Light southwest wind.
Saturday
A 20 percent chance of showers before 1pm. Sunny, with a high near 87.
Saturday Night
Mostly clear, with a low around 66.
Sunday
Mostly sunny, with a high near 84.
Sunday Night
A slight chance of showers and thunderstorms. Mostly cloudy, with a low around 66. Chance of precipitation is 20%.
Monday
Mostly sunny, with a high near 85.
Monday Night
Partly cloudy, with a low around 67.
Tuesday
Mostly sunny, with a high near 88.
Tuesday Night
Partly cloudy, with a low around 69.
Wednesday
Mostly sunny, with a high near 89.
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ABOUT THIS FORECAST

 
Point Forecast:
3 Miles SSE St. Charles County Smartt Airport MO
 38.89°N 90.39°W (Elev. 427 ft)
Last Update:
1:20 am CDT Aug 20, 2026
Forecast Valid:
1am CDT Aug 20, 2026-6pm CDT Aug 26, 2026
 
Forecast Discussion
 
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Additional Resources

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National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation