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.

Fair

67°F

19°C

Humidity 73%
Wind Speed SE 3 mph
Barometer 29.89 in (1011.8 mb)
Dewpoint 58°F (14°C)
Visibility 10.00 mi
Last update 13 Oct 1:53 am CDT
Extended Forecast for

Herculaneum MO

  • Overnight

    Overnight: Clear, with a low around 67. Light and variable wind.

    Low: 67 °F

    Clear

  • Tuesday

    Tuesday: Sunny, with a high near 96. Heat index values as high as 103. Southwest wind 3 to 7 mph.

    High: 96 °F

    Sunny

  • Tuesday Night

    Tuesday Night: A 30 percent chance of showers and thunderstorms, mainly after 4am. Mostly clear, with a low around 71. South wind 3 to 7 mph.

    Low: 71 °F

    Mostly Clear
    then Chance
    T-storms

  • Wednesday

    Wednesday: Showers and possibly a thunderstorm. High near 83. Light west wind. Chance of precipitation is 90%.

    High: 83 °F

    Showers

  • Wednesday Night

    Wednesday Night: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 65. Calm wind. Chance of precipitation is 70%.

    Low: 65 °F

    Chance
    T-storms then
    Showers
    Likely

  • Thursday

    Thursday: Showers and possibly a thunderstorm. High near 84. Chance of precipitation is 80%.

    High: 84 °F

    Showers

  • Thursday Night

    Thursday Night: A chance of showers and thunderstorms before 1am, then a slight chance of showers. Mostly cloudy, with a low around 52. Chance of precipitation is 30%.

    Low: 52 °F

    Chance
    Showers

  • Friday

    Friday: Partly sunny, with a high near 65.

    High: 65 °F

    Partly Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 37.

    Low: 37 °F

    Mostly Clear

Detailed Forecast

Overnight
Clear, with a low around 67. Light and variable wind.
Tuesday
Sunny, with a high near 96. Heat index values as high as 103. Southwest wind 3 to 7 mph.
Tuesday Night
A 30 percent chance of showers and thunderstorms, mainly after 4am. Mostly clear, with a low around 71. South wind 3 to 7 mph.
Wednesday
Showers and possibly a thunderstorm. High near 83. Light west wind. Chance of precipitation is 90%.
Wednesday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 65. Calm wind. Chance of precipitation is 70%.
Thursday
Showers and possibly a thunderstorm. High near 84. Chance of precipitation is 80%.
Thursday Night
A chance of showers and thunderstorms before 1am, then a slight chance of showers. Mostly cloudy, with a low around 52. Chance of precipitation is 30%.
Friday
Partly sunny, with a high near 65.
Friday Night
Mostly clear, with a low around 37.
Saturday
Sunny, with a high near 64.
Saturday Night
Mostly clear, with a low around 36.
Sunday
Sunny, with a high near 72.
Sunday Night
Mostly clear, with a low around 44.
Monday
Mostly sunny, with a high near 77.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Herculaneum MO
 38.25°N 90.39°W (Elev. 499 ft)
Last Update:
1:21 am CDT Oct 13, 2026
Forecast Valid:
2am CDT Oct 13, 2026-6pm CDT Oct 19, 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