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, Spirit Of St. Louis Airport (KSUS)

Lat: 38.66°NLon: 90.66°WElev: 463ft.

Fair

80°F

27°C

Humidity 74%
Wind Speed SW 12 mph
Barometer 29.98 in (1014.1 mb)
Dewpoint 71°F (22°C)
Visibility 10.00 mi
Heat Index83°F (28°C)
Last update 11 Aug 7:54 am CDT
Extended Forecast for

Byrnes Mill MO

Extreme Heat Warning August 11, 08:43am until August 12, 08:00pm
Click here for hazard details and duration
Extreme Heat Warning
  •  
    Extreme Heat Warning August 11, 08:43am until August 12, 08:00pm

    NOW until 8:00pm Wed

    Extreme Heat Warning

  • Today

    High: 97 °F

    Hot

  • Tonight

    Tonight: Partly cloudy, with a low around 76. Light southwest wind.

    Low: 76 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Sunny and hot, with a high near 98. Heat index values as high as 110. Southwest wind 3 to 5 mph.

    High: 98 °F

    Hot

  • Wednesday Night

    Wednesday Night: A 20 percent chance of showers and thunderstorms after 1am.  Partly cloudy, with a low around 76. Light southwest wind.

    Low: 76 °F

    Mostly Clear
    then Slight
    Chance
    T-storms

  • Thursday

    Thursday: A 20 percent chance of showers and thunderstorms after 1pm.  Mostly sunny, with a high near 96. Light and variable wind.

    High: 96 °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 74.

    Low: 74 °F

    Slight Chance
    T-storms

  • Friday

    Friday: Mostly sunny, with a high near 94.

    High: 94 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 74.

    Low: 74 °F

    Partly Cloudy

Detailed Forecast

Today
Mostly sunny and hot, with a high near 97. Heat index values as high as 106. Southwest wind 5 to 7 mph.
Tonight
Partly cloudy, with a low around 76. Light southwest wind.
Wednesday
Sunny and hot, with a high near 98. Heat index values as high as 110. Southwest wind 3 to 5 mph.
Wednesday Night
A 20 percent chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 76. Light southwest wind.
Thursday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 96. Light and variable wind.
Thursday Night
A 20 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 74.
Friday
Mostly sunny, with a high near 94.
Friday Night
Partly cloudy, with a low around 74.
Saturday
Mostly sunny and hot, with a high near 98.
Saturday Night
Mostly clear, with a low around 76.
Sunday
Sunny and hot, with a high near 97.
Sunday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 73.
Monday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 87.
Basemap Options
Click map to change the forecast location
Loading map...

ABOUT THIS FORECAST

 
Point Forecast:
Byrnes Mill MO
 38.43°N 90.58°W (Elev. 495 ft)
6:06 am CDT Aug 11, 2026
8am CDT Aug 11, 2026-6pm CDT Aug 17, 2026
 
Get as KML Get as XML

Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

Hourly Weather Forecast

National Digital Forecast Database