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

60°F

16°C

Humidity 38%
Wind Speed SE 9 mph
Barometer 30.31 in (1026.5 mb)
Dewpoint 34°F (1°C)
Visibility 10.00 mi
Last update 20 Apr 12:53 pm CDT
Extended Forecast for

Herculaneum MO

  • This Afternoon

    This Afternoon: Sunny, with a high near 70. Southeast wind 3 to 6 mph.

    High: 70 °F

    Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 51. Southeast wind around 6 mph becoming light and variable.

    Low: 51 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny, with a high near 79. Southwest wind 5 to 10 mph, with gusts as high as 21 mph.

    High: 79 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 53. Southwest wind 5 to 7 mph.

    Low: 53 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny, with a high near 79. Southwest wind 3 to 6 mph.

    High: 79 °F

    Sunny

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 55.

    Low: 55 °F

    Mostly Clear

  • Thursday

    Thursday: Mostly sunny, with a high near 81.

    High: 81 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: A slight chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 61. Chance of precipitation is 60%.

    Low: 61 °F

    Slight Chance
    T-storms then
    Showers
    Likely

  • Friday

    Friday: Showers and possibly a thunderstorm. High near 75. Chance of precipitation is 80%.

    High: 75 °F

    Showers

Detailed Forecast

This Afternoon
Sunny, with a high near 70. Southeast wind 3 to 6 mph.
Tonight
Mostly clear, with a low around 51. Southeast wind around 6 mph becoming light and variable.
Tuesday
Sunny, with a high near 79. Southwest wind 5 to 10 mph, with gusts as high as 21 mph.
Tuesday Night
Mostly clear, with a low around 53. Southwest wind 5 to 7 mph.
Wednesday
Sunny, with a high near 79. Southwest wind 3 to 6 mph.
Wednesday Night
Mostly clear, with a low around 55.
Thursday
Mostly sunny, with a high near 81.
Thursday Night
A slight chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 61. Chance of precipitation is 60%.
Friday
Showers and possibly a thunderstorm. High near 75. Chance of precipitation is 80%.
Friday Night
Showers likely and possibly a thunderstorm before 1am, then a chance of showers. Mostly cloudy, with a low around 51. Chance of precipitation is 60%.
Saturday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 72.
Saturday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 49.
Sunday
A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 72.
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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:
12:01 pm CDT Apr 20, 2026
Forecast Valid:
1pm CDT Apr 20, 2026-6pm CDT Apr 26, 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