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

82°F

28°C

Humidity 55%
Wind Speed N 6 mph
Barometer 29.92 in (1012.6 mb)
Dewpoint 64°F (18°C)
Visibility 10.00 mi
Heat Index84°F (29°C)
Last update 20 Jun 6:53 pm CDT
Extended Forecast for

Herculaneum MO

Flood Watch June 21, 07:00am until June 22, 07:00am
Click here for hazard details and duration
Flood Watch

  • Tonight

    Tonight: Partly cloudy, with a low around 66. Calm wind.

    Low: 66 °F

    Partly Cloudy

  • Sunday

    Sunday: Showers and thunderstorms likely, mainly after 5pm. Mostly cloudy, with a high near 85. Light and variable wind becoming south 5 to 10 mph in the morning. Winds could gust as high as 24 mph. Chance of precipitation is 70%.

    High: 85 °F

    T-storms
    Likely

  • Sunday Night

    Sunday Night: Showers and thunderstorms before midnight, then showers likely and possibly a thunderstorm between midnight and 1am, then a chance of showers and thunderstorms after 1am. Low around 66. Southwest wind 6 to 8 mph, with gusts as high as 20 mph. Chance of precipitation is 90%.

    Low: 66 °F

    T-storms then
    Showers
    Likely

  • Monday

    Monday: A 20 percent chance of showers before 10am. Cloudy, then gradually becoming mostly sunny, with a high near 78. Northwest wind 5 to 7 mph.

    High: 78 °F

    Slight Chance
    Showers then
    Partly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 60. North wind around 5 mph becoming calm in the evening.

    Low: 60 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 81.

    High: 81 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 61.

    Low: 61 °F

    Mostly Clear

  • Wednesday

    Wednesday: Mostly sunny, with a high near 84.

    High: 84 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 61.

    Low: 61 °F

    Partly Cloudy

Detailed Forecast

Tonight
Partly cloudy, with a low around 66. Calm wind.
Sunday
Showers and thunderstorms likely, mainly after 5pm. Mostly cloudy, with a high near 85. Light and variable wind becoming south 5 to 10 mph in the morning. Winds could gust as high as 24 mph. Chance of precipitation is 70%.
Sunday Night
Showers and thunderstorms before midnight, then showers likely and possibly a thunderstorm between midnight and 1am, then a chance of showers and thunderstorms after 1am. Low around 66. Southwest wind 6 to 8 mph, with gusts as high as 20 mph. Chance of precipitation is 90%.
Monday
A 20 percent chance of showers before 10am. Cloudy, then gradually becoming mostly sunny, with a high near 78. Northwest wind 5 to 7 mph.
Monday Night
Partly cloudy, with a low around 60. North wind around 5 mph becoming calm in the evening.
Tuesday
Mostly sunny, with a high near 81.
Tuesday Night
Mostly clear, with a low around 61.
Wednesday
Mostly sunny, with a high near 84.
Wednesday Night
Partly cloudy, with a low around 61.
Thursday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 83.
Thursday Night
A 20 percent chance of showers. Partly cloudy, with a low around 61.
Friday
A 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 84.
Friday Night
A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 65.
Saturday
A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 86.
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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:
6:41 pm CDT Jun 20, 2026
Forecast Valid:
7pm CDT Jun 20, 2026-6pm CDT Jun 27, 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