National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Heavy Rainfall and Flooding Threats in the Midwest and Ohio Valley; Heat Continues in the Plains and Southeast

An active pattern will continue to bring heavy to excessive rainfall and flash flooding threats to the Midwest and Ohio Valley over the next couple of days. Dangerous heat continues across the central/southern Plains and Southeast U.S. into next week. There is potential for record-tying/breaking temperatures with many areas forecast to see their hottest temperatures so far this year. Read More >

Hazardous Weather Conditions

Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

89°F

32°C

Humidity 68%
Wind Speed Vrbl 3 mph
Barometer 29.92 in (1012.7 mb)
Dewpoint 77°F (25°C)
Visibility 10.00 mi
Heat Index102°F (39°C)
Last update 13 Aug 11:53 am CDT
Extended Forecast for

Arnold MO

Extreme Heat Warning August 13, 12:08pm until August 15, 09:00pm
Click here for hazard details and duration
Extreme Heat Warning
  •  
    Extreme Heat Warning August 13, 12:08pm until August 15, 09:00pm

    NOW until 9:00pm Sat

    Extreme Heat Warning

  • This Afternoon

    High: 98 °F

    Slight Chance
    T-storms

  • Tonight

    Tonight: Partly cloudy, with a low around 77. Southeast wind around 5 mph.

    Low: 77 °F

    Partly Cloudy

  • Friday

    Friday: Mostly sunny and hot, with a high near 100. Heat index values as high as 115. Light and variable wind becoming southwest around 5 mph.

    High: 100 °F

    Hot

  • Friday Night

    Friday Night: Mostly clear, with a low around 77. Light south wind.

    Low: 77 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny and hot, with a high near 101. West wind 3 to 5 mph.

    High: 101 °F

    Hot

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 77.

    Low: 77 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny and hot, with a high near 100.

    High: 100 °F

    Hot

  • Sunday Night

    Sunday Night: A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 74.

    Low: 74 °F

    Chance
    T-storms

Detailed Forecast

This Afternoon
A 20 percent chance of showers and thunderstorms after 3pm. Mostly sunny and hot, with a high near 98. Heat index values as high as 115. South wind 3 to 5 mph.
Tonight
Partly cloudy, with a low around 77. Southeast wind around 5 mph.
Friday
Mostly sunny and hot, with a high near 100. Heat index values as high as 115. Light and variable wind becoming southwest around 5 mph.
Friday Night
Mostly clear, with a low around 77. Light south wind.
Saturday
Sunny and hot, with a high near 101. West wind 3 to 5 mph.
Saturday Night
Mostly clear, with a low around 77.
Sunday
Sunny and hot, with a high near 100.
Sunday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 74.
Monday
A 30 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 89.
Monday Night
Partly cloudy, with a low around 70.
Tuesday
Mostly sunny, with a high near 89.
Tuesday Night
Mostly clear, with a low around 71.
Wednesday
Mostly sunny, with a high near 94.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Arnold MO
 38.42°N 90.38°W (Elev. 495 ft)
Last Update:
4:26 am CDT Aug 13, 2026
Forecast Valid:
12pm CDT Aug 13, 2026-6pm CDT Aug 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