Heavy to Excessive Rains in The Four Corners Region and Midwest; Heat Persists in the South-Central U.S.

Repeated rounds of showers and thunderstorms could bring a flash flooding threat across the Four Corners region and from the mid-Mississippi Valley into the lower Great Lakes. Hot temperatures and high humidity will continue to challenge daily records from the Southern Plains to the lower Mississippi Valley. Read More >

Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

77°F

25°C

Humidity 94%
Wind Speed Calm
Barometer 30.20 in (1022.3 mb)
Dewpoint 75°F (24°C)
Visibility 10.00 mi
Heat Index78°F (26°C)
Last update 16 Sep 5:53 pm CDT
Extended Forecast for

Herculaneum MO

Heat Advisory September 16, 06:29pm until September 19, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory September 16, 06:29pm until September 19, 08:00pm

    NOW until 8:00pm Sat

    Heat Advisory

  • Tonight

    Low: 72 °F

    Chance
    T-storms then
    Partly Cloudy

  • Thursday

    Thursday: A slight chance of showers and thunderstorms between 1pm and 3pm.  Sunny and hot, with a high near 98. Heat index values as high as 107. Calm wind becoming west around 6 mph.  Chance of precipitation is 20%.

    High: 98 °F

    Sunny then
    Slight Chance
    T-storms

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 72. Light and variable wind.

    Low: 72 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 96. Heat index values as high as 106. Calm wind.

    High: 96 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 70. Calm wind.

    Low: 70 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny and hot, with a high near 97.

    High: 97 °F

    Hot

  • Saturday Night

    Saturday Night: A 20 percent chance of showers and thunderstorms after 1am.  Partly cloudy, with a low around 70.

    Low: 70 °F

    Partly Cloudy
    then Slight
    Chance
    T-storms

  • Sunday

    Sunday: A 20 percent chance of showers after 1pm.  Mostly sunny, with a high near 94.

    High: 94 °F

    Mostly Sunny
    then Slight
    Chance
    Showers

Detailed Forecast

Tonight
A 50 percent chance of showers and thunderstorms, mainly before 9pm. Cloudy during the early evening, then gradual clearing, with a low around 72. Calm wind.
Thursday
A slight chance of showers and thunderstorms between 1pm and 3pm. Sunny and hot, with a high near 98. Heat index values as high as 107. Calm wind becoming west around 6 mph. Chance of precipitation is 20%.
Thursday Night
Mostly clear, with a low around 72. Light and variable wind.
Friday
Sunny, with a high near 96. Heat index values as high as 106. Calm wind.
Friday Night
Mostly clear, with a low around 70. Calm wind.
Saturday
Sunny and hot, with a high near 97.
Saturday Night
A 20 percent chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 70.
Sunday
A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 94.
Sunday Night
A 20 percent chance of showers and thunderstorms before 1am. Partly cloudy, with a low around 67.
Monday
A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 88. Chance of precipitation is 30%.
Monday Night
A 30 percent chance of showers. Mostly cloudy, with a low around 63.
Tuesday
A 20 percent chance of showers. Mostly sunny, with a high near 83.
Tuesday Night
Partly cloudy, with a low around 60.
Wednesday
A 20 percent chance of showers. Mostly sunny, with a high near 83.
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ABOUT THIS FORECAST

 
Point Forecast:
Herculaneum MO
 38.27°N 90.39°W (Elev. 456 ft)
6:06 pm CDT Sep 16, 2026
6pm CDT Sep 16, 2026-6pm CDT Sep 23, 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