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

Hazardous Weather Conditions

Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

79°F

26°C

Humidity 90%
Wind Speed SW 3 mph
Barometer 30.03 in (1016.4 mb)
Dewpoint 76°F (24°C)
Visibility 10.00 mi
Heat Index83°F (28°C)
Last update 16 Aug 9:53 pm CDT
Extended Forecast for

Herculaneum MO

Heat Advisory August 16, 10:49pm until August 18, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 16, 10:49pm until August 18, 08:00pm

    NOW until 8:00pm Mon

    Heat Advisory

  • Tonight

    Low: 73 °F

    Partly Cloudy

  • Sunday

    Sunday: A 30 percent chance of showers and thunderstorms, mainly after 4pm. Mostly sunny and hot, with a high near 98. Heat index values as high as 109. Calm wind.

    High: 98 °F

    Sunny then
    Chance
    T-storms

  • Sunday Night

    Sunday Night: A 30 percent chance of showers and thunderstorms, mainly before 8pm. Partly cloudy, with a low around 73. Calm wind.

    Low: 73 °F

    Chance
    T-storms then
    Mostly Clear

  • Monday

    Monday: Sunny and hot, with a high near 98. Heat index values as high as 110. Calm wind.

    High: 98 °F

    Hot

  • Monday Night

    Monday Night: Mostly clear, with a low around 75. Calm wind.

    Low: 75 °F

    Mostly Clear

  • Tuesday

    Tuesday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny and hot, with a high near 97.

    High: 97 °F

    Sunny then
    Slight Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 71.

    Low: 71 °F

    Chance
    T-storms

  • Wednesday

    Wednesday: A 30 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 84.

    High: 84 °F

    Chance
    T-storms

Detailed Forecast

Tonight
Partly cloudy, with a low around 73. Calm wind.
Sunday
A 30 percent chance of showers and thunderstorms, mainly after 4pm. Mostly sunny and hot, with a high near 98. Heat index values as high as 109. Calm wind.
Sunday Night
A 30 percent chance of showers and thunderstorms, mainly before 8pm. Partly cloudy, with a low around 73. Calm wind.
Monday
Sunny and hot, with a high near 98. Heat index values as high as 110. Calm wind.
Monday Night
Mostly clear, with a low around 75. Calm wind.
Tuesday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny and hot, with a high near 97.
Tuesday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 71.
Wednesday
A 30 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 84.
Wednesday Night
Partly cloudy, with a low around 67.
Thursday
Mostly sunny, with a high near 83.
Thursday Night
Mostly clear, with a low around 65.
Friday
Sunny, with a high near 88.
Friday Night
Mostly clear, with a low around 65.
Saturday
Sunny, with a high near 91.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Herculaneum MO
 38.27°N 90.39°W (Elev. 456 ft)
Last Update:
5:56 pm CDT Aug 16, 2025
Forecast Valid:
10pm CDT Aug 16, 2025-6pm CDT Aug 23, 2025
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

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Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation