Severe Thunderstorms and Heavy Rain in the Mid-Atlantic; Heat Persists Across the South

Scattered severe thunderstorms and excessive rainfall are possible into the night in the Mid Atlantic, and heavy rain will shift to Virginia and the Carolinas on Friday. Severe thunderstorms are also possible in the Central Plains into the Upper MS Valley and the Deep South tonight. Dangerous heat persists across the Southern Plains and Lower MS Valley and heat will expand into the Southwest. Read More >

Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

65°F

18°C

Humidity 100%
Wind Speed Calm
Barometer 30.06 in (1017.4 mb)
Dewpoint 65°F (18°C)
Visibility 7.00 mi
Last update 21 Aug 4:53 am CDT
Extended Forecast for

Herculaneum MO

  • Today

    Today: Patchy fog before 9am.  Otherwise, sunny, with a high near 87. Calm wind.

    High: 87 °F

    Patchy Fog
    then Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 67. Calm wind.

    Low: 67 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 86. Calm wind becoming north around 6 mph in the afternoon.

    High: 86 °F

    Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 63. Light north wind.

    Low: 63 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 82. Light north wind.

    High: 82 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 61.

    Low: 61 °F

    Mostly Cloudy

  • Monday

    Monday: A 30 percent chance of showers and thunderstorms.  Partly sunny, with a high near 80.

    High: 80 °F

    Chance
    T-storms

  • Monday Night

    Monday Night: A 40 percent chance of showers and thunderstorms.  Partly cloudy, with a low around 63.

    Low: 63 °F

    Chance
    T-storms

  • Tuesday

    Tuesday: A 20 percent chance of showers and thunderstorms before 1pm.  Mostly sunny, with a high near 84.

    High: 84 °F

    Slight Chance
    T-storms

Detailed Forecast

Today
Patchy fog before 9am. Otherwise, sunny, with a high near 87. Calm wind.
Tonight
Mostly clear, with a low around 67. Calm wind.
Saturday
Sunny, with a high near 86. Calm wind becoming north around 6 mph in the afternoon.
Saturday Night
Mostly clear, with a low around 63. Light north wind.
Sunday
Sunny, with a high near 82. Light north wind.
Sunday Night
Mostly cloudy, with a low around 61.
Monday
A 30 percent chance of showers and thunderstorms. Partly sunny, with a high near 80.
Monday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 63.
Tuesday
A 20 percent chance of showers and thunderstorms before 1pm. Mostly sunny, with a high near 84.
Tuesday Night
A 20 percent chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 66.
Wednesday
Partly sunny, with a high near 87.
Wednesday Night
Partly cloudy, with a low around 65.
Thursday
Mostly sunny, with a high near 86.
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ABOUT THIS FORECAST

 
Point Forecast:
Herculaneum MO
 38.27°N 90.39°W (Elev. 456 ft)
4:41 am CDT Aug 21, 2026
5am CDT Aug 21, 2026-6pm CDT Aug 27, 2026
 
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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