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.

Thunderstorm in Vicinity

84°F

29°C

Humidity 77%
Wind Speed NW 5 mph
Barometer 30.05 in (1017.3 mb)
Dewpoint 76°F (24°C)
Visibility 10.00 mi
Heat Index93°F (34°C)
Last update 16 Aug 3:53 pm CDT
Extended Forecast for

Arnold MO

Heat Advisory August 16, 04:46pm until August 18, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 16, 04:46pm until August 18, 08:00pm

    NOW until 8:00pm Mon

    Heat Advisory

  • This Afternoon

    High: 98 °F

    Isolated
    T-storms

  • Tonight

    Tonight: Isolated showers and thunderstorms before 9pm. Partly cloudy, with a low around 75. Southeast wind around 5 mph becoming calm after midnight. Chance of precipitation is 20%.

    Low: 75 °F

    Isolated
    T-storms then
    Mostly Clear

  • Sunday

    Sunday: Scattered showers and thunderstorms, mainly after 4pm. Mostly sunny and hot, with a high near 98. Heat index values as high as 107. Calm wind becoming east around 5 mph in the afternoon. Chance of precipitation is 30%.

    High: 98 °F

    Sunny then
    Scattered
    T-storms

  • Sunday Night

    Sunday Night: Scattered showers and thunderstorms before 10pm. Partly cloudy, with a low around 74. Calm wind. Chance of precipitation is 30%.

    Low: 74 °F

    Scattered
    T-storms then
    Mostly Clear

  • Monday

    Monday: Sunny and hot, with a high near 98. Light south wind.

    High: 98 °F

    Hot

  • Monday Night

    Monday Night: Mostly clear, with a low around 75.

    Low: 75 °F

    Mostly Clear

  • Tuesday

    Tuesday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny and hot, with a high near 97.

    High: 97 °F

    Sunny then
    Slight Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A 30 percent chance of showers and thunderstorms, mainly before 1am. Partly cloudy, with a low around 72.

    Low: 72 °F

    Chance
    T-storms

Detailed Forecast

This Afternoon
Isolated showers and thunderstorms. Mostly sunny and hot, with a high near 98. Heat index values as high as 107. South wind around 5 mph. Chance of precipitation is 20%.
Tonight
Isolated showers and thunderstorms before 9pm. Partly cloudy, with a low around 75. Southeast wind around 5 mph becoming calm after midnight. Chance of precipitation is 20%.
Sunday
Scattered showers and thunderstorms, mainly after 4pm. Mostly sunny and hot, with a high near 98. Heat index values as high as 107. Calm wind becoming east around 5 mph in the afternoon. Chance of precipitation is 30%.
Sunday Night
Scattered showers and thunderstorms before 10pm. Partly cloudy, with a low around 74. Calm wind. Chance of precipitation is 30%.
Monday
Sunny and hot, with a high near 98. Light south wind.
Monday Night
Mostly clear, with a low around 75.
Tuesday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny and hot, with a high near 97.
Tuesday Night
A 30 percent chance of showers and thunderstorms, mainly before 1am. Partly cloudy, with a low around 72.
Wednesday
A 20 percent chance of showers and thunderstorms. Partly sunny, with a high near 84.
Wednesday Night
Partly cloudy, with a low around 67.
Thursday
Mostly sunny, with a high near 84.
Thursday Night
Mostly clear, with a low around 65.
Friday
Sunny, with a high near 88.
Friday Night
Mostly clear, with a low around 66.
Saturday
Sunny, with a high near 91.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Arnold MO
 38.4°N 90.38°W (Elev. 495 ft)
Last Update:
4:16 pm CDT Aug 16, 2025
Forecast Valid:
4pm CDT Aug 16, 2025-6pm CDT Aug 23, 2025
 
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