Thunderstorms and Heavy Rain in the Mid-South; Heat Continues in the Southeast and Southwest

Severe thunderstorms and heavy rain are expected across portions of the mid-Mississippi Valley into the Ohio Valley and portions of Arizona. Dangerous heat persists in the South and Southeast while building into the Southwest. Overnight lows will be so warm that, when combined with oppressive dew points, 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.

Fair

72°F

22°C

Humidity 94%
Wind Speed E 6 mph
Barometer 29.93 in (1012.9 mb)
Dewpoint 70°F (21°C)
Visibility 10.00 mi
Last update 18 Aug 10:54 pm CDT
Extended Forecast for

3 Miles ENE Portage Des Sioux MO

  • Tonight

    Tonight: Showers and thunderstorms, mainly after 3am.  Low around 70. Light and variable wind.  Chance of precipitation is 90%.

    Low: 70 °F

    T-storms

  • Wednesday

    Wednesday: Showers and thunderstorms likely, mainly before noon.  Mostly cloudy, with a high near 82. West wind around 5 mph becoming light and variable.  Chance of precipitation is 70%.

    High: 82 °F

    T-storms
    Likely then
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A 30 percent chance of showers and thunderstorms, mainly before 10pm.  Mostly cloudy, with a low around 67. Northeast wind around 5 mph becoming calm  in the evening.

    Low: 67 °F

    Chance
    T-storms then
    Mostly Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 85. Northeast wind 3 to 6 mph.

    High: 85 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 65. Northeast wind around 5 mph becoming calm  in the evening.

    Low: 65 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 87.

    High: 87 °F

    Sunny

  • Friday Night

    Friday Night: A 20 percent chance of showers and thunderstorms.  Mostly clear, with a low around 67.

    Low: 67 °F

    Slight Chance
    T-storms

  • Saturday

    Saturday: A slight chance of showers, with thunderstorms also possible after 1pm.  Sunny, with a high near 86. Chance of precipitation is 20%.

    High: 86 °F

    Slight Chance
    Showers then
    Slight Chance
    T-storms

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 64.

    Low: 64 °F

    Mostly Clear

Detailed Forecast

Tonight
Showers and thunderstorms, mainly after 3am. Low around 70. Light and variable wind. Chance of precipitation is 90%.
Wednesday
Showers and thunderstorms likely, mainly before noon. Mostly cloudy, with a high near 82. West wind around 5 mph becoming light and variable. Chance of precipitation is 70%.
Wednesday Night
A 30 percent chance of showers and thunderstorms, mainly before 10pm. Mostly cloudy, with a low around 67. Northeast wind around 5 mph becoming calm in the evening.
Thursday
Mostly sunny, with a high near 85. Northeast wind 3 to 6 mph.
Thursday Night
Mostly clear, with a low around 65. Northeast wind around 5 mph becoming calm in the evening.
Friday
Sunny, with a high near 87.
Friday Night
A 20 percent chance of showers and thunderstorms. Mostly clear, with a low around 67.
Saturday
A slight chance of showers, with thunderstorms also possible after 1pm. Sunny, with a high near 86. Chance of precipitation is 20%.
Saturday Night
Mostly clear, with a low around 64.
Sunday
Mostly sunny, with a high near 83.
Sunday Night
A 30 percent chance of showers. Partly cloudy, with a low around 64.
Monday
A 20 percent chance of showers. Mostly sunny, with a high near 86.
Monday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 67.
Tuesday
Mostly sunny, with a high near 88.
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ABOUT THIS FORECAST

 
Point Forecast:
3 Miles ENE Portage Des Sioux MO
 38.93°N 90.27°W (Elev. 407 ft)
10:26 pm CDT Aug 18, 2026
11pm CDT Aug 18, 2026-6pm CDT Aug 25, 2026
 
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Additional Resources

Radar & Satellite Image

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Hourly Weather Forecast

National Digital Forecast Database