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.

Fog/Mist

73°F

23°C

Humidity 96%
Wind Speed SE 5 mph
Barometer 29.97 in (1014.3 mb)
Dewpoint 72°F (22°C)
Visibility 6.00 mi
Last update 9 Jul 1:53 am CDT
Extended Forecast for

Arnold MO

  • Overnight

    Overnight: Partly cloudy, with a low around 72. Calm wind.

    Low: 72 °F

    Partly Cloudy

  • Thursday

    Thursday: A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 94. Heat index values as high as 105. Southwest wind 3 to 7 mph. Chance of precipitation is 50%.

    High: 94 °F

    Mostly Sunny
    then Chance
    T-storms

  • Thursday Night

    Thursday Night: A chance of showers and thunderstorms before 11pm, then showers likely and possibly a thunderstorm between 11pm and midnight, then a chance of showers and thunderstorms after midnight. Mostly cloudy, with a low around 73. Southwest wind around 5 mph becoming light and variable. Chance of precipitation is 70%.

    Low: 73 °F

    Showers
    Likely then
    Chance
    T-storms

  • Friday

    Friday: A 30 percent chance of showers and thunderstorms, mainly after 4pm. Partly sunny, with a high near 90. Heat index values as high as 100. Light and variable wind becoming west 5 to 7 mph in the morning.

    High: 90 °F

    Chance
    T-storms

  • Friday Night

    Friday Night: A chance of showers and thunderstorms before 7pm, then showers likely and possibly a thunderstorm between 7pm and 4am, then showers likely after 4am. Mostly cloudy, with a low around 72. Northwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 60%.

    Low: 72 °F

    Showers
    Likely

  • Saturday

    Saturday: A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 88. Chance of precipitation is 40%.

    High: 88 °F

    Chance
    Showers

  • Saturday Night

    Saturday Night: A 30 percent chance of showers before 1am. Partly cloudy, with a low around 70.

    Low: 70 °F

    Chance
    Showers

  • Sunday

    Sunday: A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 88.

    High: 88 °F

    Mostly Sunny
    then Slight
    Chance
    Showers

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 69.

    Low: 69 °F

    Mostly Clear

Detailed Forecast

Overnight
Partly cloudy, with a low around 72. Calm wind.
Thursday
A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 94. Heat index values as high as 105. Southwest wind 3 to 7 mph. Chance of precipitation is 50%.
Thursday Night
A chance of showers and thunderstorms before 11pm, then showers likely and possibly a thunderstorm between 11pm and midnight, then a chance of showers and thunderstorms after midnight. Mostly cloudy, with a low around 73. Southwest wind around 5 mph becoming light and variable. Chance of precipitation is 70%.
Friday
A 30 percent chance of showers and thunderstorms, mainly after 4pm. Partly sunny, with a high near 90. Heat index values as high as 100. Light and variable wind becoming west 5 to 7 mph in the morning.
Friday Night
A chance of showers and thunderstorms before 7pm, then showers likely and possibly a thunderstorm between 7pm and 4am, then showers likely after 4am. Mostly cloudy, with a low around 72. Northwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 60%.
Saturday
A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 88. Chance of precipitation is 40%.
Saturday Night
A 30 percent chance of showers before 1am. Partly cloudy, with a low around 70.
Sunday
A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 88.
Sunday Night
Mostly clear, with a low around 69.
Monday
Sunny, with a high near 90.
Monday Night
Mostly clear, with a low around 71.
Tuesday
Sunny, with a high near 92.
Tuesday Night
Clear, with a low around 72.
Wednesday
Sunny, with a high near 94.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Arnold MO
 38.45°N 90.38°W (Elev. 499 ft)
Last Update:
1:26 am CDT Jul 9, 2026
Forecast Valid:
2am CDT Jul 9, 2026-6pm CDT Jul 15, 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