Severe Thunderstorms and Heavy Rain Across the Ohio Valley;

Severe thunderstorms with damaging wind gusts will be possible from the mid-Mississippi Valley into parts of the Ohio Valley and central Appalachians. Heavy rain associated with these storms may lead to considerable flash and urban flooding impacts across portions of the Ohio Valley. Mid-summer heat persists from the Central Plains to the Southeast. Read More >

Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

79°F

26°C

Humidity 79%
Wind Speed S 5 mph
Barometer 29.98 in (1014.6 mb)
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Heat Index82°F (28°C)
Last update 11 Aug 6:53 am CDT
Extended Forecast for

Arnold MO

Extreme Heat Warning August 11, 07:44am until August 12, 08:00pm
Click here for hazard details and duration
Extreme Heat Warning
  •  
    Extreme Heat Warning August 11, 07:44am until August 12, 08:00pm

    NOW until 8:00pm Wed

    Extreme Heat Warning

  • Today

    High: 98 °F

    Hot

  • Tonight

    Tonight: Partly cloudy, with a low around 77. Southwest wind around 6 mph.

    Low: 77 °F

    Partly Cloudy

  • Wednesday

    Wednesday: A 20 percent chance of showers and thunderstorms after 4pm.  Mostly sunny and hot, with a high near 99. Heat index values as high as 113. Southwest wind around 6 mph.

    High: 99 °F

    Sunny then
    Slight Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A 20 percent chance of showers and thunderstorms after 1am.  Partly cloudy, with a low around 77. Light south wind.

    Low: 77 °F

    Partly Cloudy
    then Slight
    Chance
    T-storms

  • Thursday

    Thursday: A 20 percent chance of showers and thunderstorms after 1pm.  Mostly sunny and hot, with a high near 97. Light and variable wind becoming southwest around 5 mph in the morning.

    High: 97 °F

    Partly Sunny
    then Slight
    Chance
    T-storms

  • Thursday Night

    Thursday Night: A 20 percent chance of showers and thunderstorms.  Mostly cloudy, with a low around 75.

    Low: 75 °F

    Slight Chance
    T-storms

  • Friday

    Friday: Partly sunny, with a high near 95.

    High: 95 °F

    Partly Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 75.

    Low: 75 °F

    Partly Cloudy

Detailed Forecast

Today
Mostly sunny and hot, with a high near 98. Heat index values as high as 106. Southwest wind 6 to 8 mph.
Tonight
Partly cloudy, with a low around 77. Southwest wind around 6 mph.
Wednesday
A 20 percent chance of showers and thunderstorms after 4pm. Mostly sunny and hot, with a high near 99. Heat index values as high as 113. Southwest wind around 6 mph.
Wednesday Night
A 20 percent chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 77. Light south wind.
Thursday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny and hot, with a high near 97. Light and variable wind becoming southwest around 5 mph in the morning.
Thursday Night
A 20 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 75.
Friday
Partly sunny, with a high near 95.
Friday Night
Partly cloudy, with a low around 75.
Saturday
Mostly sunny and hot, with a high near 100.
Saturday Night
Mostly clear, with a low around 77.
Sunday
Sunny and hot, with a high near 99.
Sunday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 74.
Monday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 88.
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ABOUT THIS FORECAST

 
Point Forecast:
Arnold MO
 38.42°N 90.38°W (Elev. 495 ft)
6:06 am CDT Aug 11, 2026
7am CDT Aug 11, 2026-6pm CDT Aug 17, 2026
 
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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