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

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Mostly Cloudy

61°F

16°C

Humidity 87%
Wind Speed Calm
Barometer 29.94 in (1013.4 mb)
Dewpoint 57°F (14°C)
Visibility 10.00 mi
Last update 15 Jun 11:53 pm CDT
Extended Forecast for

Herculaneum MO

  • Overnight

    Overnight: Clear, with a low around 55. Calm wind.

    Low: 55 °F

    Clear

  • Tuesday

    Tuesday: A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Increasing clouds, with a high near 82. Calm wind becoming west 5 to 8 mph in the morning. Chance of precipitation is 40%.

    High: 82 °F

    Mostly Sunny
    then Chance
    T-storms

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 58. West wind around 6 mph becoming calm in the evening.

    Low: 58 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny, with a high near 90. Light south wind increasing to 11 to 16 mph in the morning. Winds could gust as high as 32 mph.

    High: 90 °F

    Sunny

  • Wednesday Night

    Wednesday Night: Showers and possibly a thunderstorm before 1am, then a chance of showers. Low around 70. Southwest wind 7 to 14 mph, with gusts as high as 30 mph. Chance of precipitation is 90%.

    Low: 70 °F

    Showers

  • Thursday

    Thursday: A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 81. Chance of precipitation is 40%.

    High: 81 °F

    Chance
    Showers

  • Thursday Night

    Thursday Night: A 20 percent chance of showers before 1am. Partly cloudy, with a low around 58.

    Low: 58 °F

    Slight Chance
    Showers

  • Juneteenth

    Juneteenth: Mostly sunny, with a high near 83.

    High: 83 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 60.

    Low: 60 °F

    Mostly Clear

Detailed Forecast

Overnight
Clear, with a low around 55. Calm wind.
Tuesday
A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Increasing clouds, with a high near 82. Calm wind becoming west 5 to 8 mph in the morning. Chance of precipitation is 40%.
Tuesday Night
Mostly clear, with a low around 58. West wind around 6 mph becoming calm in the evening.
Wednesday
Sunny, with a high near 90. Light south wind increasing to 11 to 16 mph in the morning. Winds could gust as high as 32 mph.
Wednesday Night
Showers and possibly a thunderstorm before 1am, then a chance of showers. Low around 70. Southwest wind 7 to 14 mph, with gusts as high as 30 mph. Chance of precipitation is 90%.
Thursday
A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 81. Chance of precipitation is 40%.
Thursday Night
A 20 percent chance of showers before 1am. Partly cloudy, with a low around 58.
Juneteenth
Mostly sunny, with a high near 83.
Friday Night
Mostly clear, with a low around 60.
Saturday
Mostly sunny, with a high near 87.
Saturday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 65.
Sunday
A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 86.
Sunday Night
Showers and thunderstorms likely. Mostly cloudy, with a low around 68. Chance of precipitation is 60%.
Monday
A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 84.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Herculaneum MO
 38.27°N 90.39°W (Elev. 456 ft)
Last Update:
9:31 pm CDT Jun 15, 2026
Forecast Valid:
12am CDT Jun 16, 2026-6pm CDT Jun 22, 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