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.

Overcast

80°F

27°C

Humidity 87%
Wind Speed Calm
Barometer 29.92 in (1012.9 mb)
Dewpoint 76°F (24°C)
Visibility 10.00 mi
Heat Index85°F (29°C)
Last update 27 Jun 10:53 am CDT
Extended Forecast for

Herculaneum MO

Extreme Heat Watch June 28, 12:00pm until July 3, 12:00am
Click here for hazard details and duration
Extreme Heat Watch

  • Today

    Today: Showers and thunderstorms, mainly before 2pm. High near 85. Calm wind becoming southwest around 5 mph. Chance of precipitation is 80%.

    High: 85 °F

    T-storms

  • Tonight

    Tonight: A 30 percent chance of showers and thunderstorms, mainly between 10pm and 4am. Partly cloudy, with a low around 71. Calm wind.

    Low: 71 °F

    Chance
    T-storms

  • Sunday

    Sunday: Sunny, with a high near 93. Heat index values as high as 103. Calm wind becoming south around 6 mph in the morning.

    High: 93 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 74. South wind around 5 mph becoming calm in the evening.

    Low: 74 °F

    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 95. South wind 3 to 6 mph.

    High: 95 °F

    Sunny

  • Monday Night

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

    Low: 75 °F

    Mostly Clear

  • Tuesday

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

    High: 97 °F

    Hot

  • Tuesday Night

    Tuesday Night: Clear, with a low around 75.

    Low: 75 °F

    Clear

  • Wednesday

    Wednesday: Sunny, with a high near 96.

    High: 96 °F

    Sunny

Detailed Forecast

Today
Showers and thunderstorms, mainly before 2pm. High near 85. Calm wind becoming southwest around 5 mph. Chance of precipitation is 80%.
Tonight
A 30 percent chance of showers and thunderstorms, mainly between 10pm and 4am. Partly cloudy, with a low around 71. Calm wind.
Sunday
Sunny, with a high near 93. Heat index values as high as 103. Calm wind becoming south around 6 mph in the morning.
Sunday Night
Mostly clear, with a low around 74. South wind around 5 mph becoming calm in the evening.
Monday
Sunny, with a high near 95. South wind 3 to 6 mph.
Monday Night
Mostly clear, with a low around 75.
Tuesday
Sunny and hot, with a high near 97.
Tuesday Night
Clear, with a low around 75.
Wednesday
Sunny, with a high near 96.
Wednesday Night
Mostly clear, with a low around 76.
Thursday
A 20 percent chance of showers and thunderstorms. Sunny, with a high near 94.
Thursday Night
Mostly clear, with a low around 75.
Friday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 94.
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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:
11:36 am CDT Jun 27, 2026
Forecast Valid:
11am CDT Jun 27, 2026-6pm CDT Jul 3, 2026
 
Forecast Discussion
 
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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

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation