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

Hazardous Weather Conditions

Current conditions at

St. Louis, Spirit Of St. Louis Airport (KSUS)

Lat: 38.66°NLon: 90.66°WElev: 463ft.

A Few Clouds

93°F

34°C

Humidity 62%
Wind Speed SW 3 mph
Barometer 29.76 in (1006.5 mb)
Dewpoint 78°F (26°C)
Visibility 10.00 mi
Heat Index109°F (43°C)
Last update 27 Jul 6:54 pm CDT
Extended Forecast for

Byrnes Mill MO

Extreme Heat Warning July 27, 07:23pm until July 28, 07:00pm
Click here for hazard details and duration
Extreme Heat Warning
  •  
    Extreme Heat Warning July 27, 07:23pm until July 28, 07:00pm

    NOW until 7:00pm Tue

    Extreme Heat Warning

  • Tonight

    Low: 79 °F

    Chance
    Showers then
    Partly Cloudy

  • Tuesday

    Tuesday: Scattered showers and thunderstorms, mainly after 5pm. Increasing clouds, with a high near 91. Heat index values as high as 105. Calm wind becoming north around 6 mph in the morning. Chance of precipitation is 30%.

    High: 91 °F

    Mostly Sunny
    then
    Scattered
    T-storms

  • Tuesday Night

    Tuesday Night: Scattered showers and thunderstorms, mainly before 10pm. Mostly cloudy, with a low around 70. North wind around 5 mph becoming calm in the evening. Chance of precipitation is 30%.

    Low: 70 °F

    Scattered
    T-storms

  • Wednesday

    Wednesday: Sunny, with a high near 88. Calm wind becoming east around 5 mph in the afternoon.

    High: 88 °F

    Sunny

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 66. Light and variable wind.

    Low: 66 °F

    Mostly Clear

  • Thursday

    Thursday: Sunny, with a high near 90.

    High: 90 °F

    Sunny

  • Thursday Night

    Thursday Night: A 30 percent chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 69.

    Low: 69 °F

    Mostly Cloudy
    then Chance
    Showers

  • Friday

    Friday: A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 86. Chance of precipitation is 50%.

    High: 86 °F

    Chance
    Showers then
    Chance
    T-storms

Detailed Forecast

Tonight
A chance of showers and thunderstorms before 10pm, then a slight chance of showers between 10pm and midnight. Partly cloudy, with a low around 79. Light southwest wind. Chance of precipitation is 30%.
Tuesday
Scattered showers and thunderstorms, mainly after 5pm. Increasing clouds, with a high near 91. Heat index values as high as 105. Calm wind becoming north around 6 mph in the morning. Chance of precipitation is 30%.
Tuesday Night
Scattered showers and thunderstorms, mainly before 10pm. Mostly cloudy, with a low around 70. North wind around 5 mph becoming calm in the evening. Chance of precipitation is 30%.
Wednesday
Sunny, with a high near 88. Calm wind becoming east around 5 mph in the afternoon.
Wednesday Night
Mostly clear, with a low around 66. Light and variable wind.
Thursday
Sunny, with a high near 90.
Thursday Night
A 30 percent chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 69.
Friday
A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 86. Chance of precipitation is 50%.
Friday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 68. Chance of precipitation is 70%.
Saturday
A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 82. Chance of precipitation is 50%.
Saturday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 67.
Sunday
A 20 percent chance of showers and thunderstorms. Sunny, with a high near 86.
Sunday Night
Mostly clear, with a low around 67.
Monday
Sunny, with a high near 85.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Byrnes Mill MO
 38.43°N 90.58°W (Elev. 495 ft)
Last Update:
6:56 pm CDT Jul 27, 2026
Forecast Valid:
7pm CDT Jul 27, 2026-6pm CDT Aug 3, 2026
 
Forecast Discussion
 
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Additional Resources

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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