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

Dangerous Heat and Heavy Rainfall into the Weekend

Hot temperatures and high humidity are forecast to continue across the mid-Mississippi Valley into this weekend. Heat Advisories remain in effect. Heavy to excessive rainfall occurring at times through the weekend could bring areas of flooding to parts of the northern Rockies, upper Midwest, central Great Lakes, and southern New England. Read More >

Hazardous Weather Conditions

Current conditions at

St. Louis Lambert International Airport (KSTL)

Lat: 38.75°NLon: 90.37°WElev: 604ft.

A Few Clouds

97°F

36°C

Humidity 40%
Wind Speed SW 8 mph
Barometer 30.05 in (1015.9 mb)
Dewpoint 69°F (21°C)
Visibility 10.00 mi
Heat Index103°F (39°C)
Last update 18 Sep 3:51 pm CDT
Extended Forecast for

Cool Valley MO

Heat Advisory September 18, 04:18pm until September 19, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory September 18, 04:18pm until September 19, 08:00pm

    NOW until 8:00pm Sat

    Heat Advisory

  • This Afternoon

    High: 98 °F

    Chance
    T-storms

  • Tonight

    Tonight: A 20 percent chance of showers and thunderstorms before 9pm. Mostly clear, with a low around 76. Light and variable wind becoming southeast around 6 mph in the evening.

    Low: 76 °F

    Slight Chance
    T-storms then
    Mostly Clear

  • Saturday

    Saturday: Mostly sunny and hot, with a high near 99. Southwest wind 5 to 8 mph.

    High: 99 °F

    Hot

  • Saturday Night

    Saturday Night: Mostly cloudy, then gradually becoming mostly clear, with a low around 76. South wind 3 to 6 mph.

    Low: 76 °F

    Decreasing
    Clouds

  • Sunday

    Sunday: A slight chance of showers, with thunderstorms also possible after 4pm. Mostly sunny, with a high near 94. West wind 5 to 7 mph. Chance of precipitation is 20%.

    High: 94 °F

    Slight Chance
    Showers then
    Slight Chance
    T-storms

  • Sunday Night

    Sunday Night: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 69. Chance of precipitation is 60%.

    Low: 69 °F

    Showers
    Likely

  • Monday

    Monday: Showers likely, with thunderstorms also possible after 1pm. Mostly cloudy, with a high near 80. Chance of precipitation is 70%.

    High: 80 °F

    Showers
    Likely

  • Monday Night

    Monday Night: A slight chance of showers and thunderstorms. Mostly cloudy, with a low around 62. Chance of precipitation is 20%.

    Low: 62 °F

    Slight Chance
    T-storms

Detailed Forecast

This Afternoon
A 30 percent chance of showers and thunderstorms, mainly after 5pm. Sunny and hot, with a high near 98. Heat index values as high as 106. Light south wind.
Tonight
A 20 percent chance of showers and thunderstorms before 9pm. Mostly clear, with a low around 76. Light and variable wind becoming southeast around 6 mph in the evening.
Saturday
Mostly sunny and hot, with a high near 99. Southwest wind 5 to 8 mph.
Saturday Night
Mostly cloudy, then gradually becoming mostly clear, with a low around 76. South wind 3 to 6 mph.
Sunday
A slight chance of showers, with thunderstorms also possible after 4pm. Mostly sunny, with a high near 94. West wind 5 to 7 mph. Chance of precipitation is 20%.
Sunday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 69. Chance of precipitation is 60%.
Monday
Showers likely, with thunderstorms also possible after 1pm. Mostly cloudy, with a high near 80. Chance of precipitation is 70%.
Monday Night
A slight chance of showers and thunderstorms. Mostly cloudy, with a low around 62. Chance of precipitation is 20%.
Tuesday
Mostly cloudy, with a high near 73.
Tuesday Night
Mostly cloudy, with a low around 57.
Wednesday
Mostly sunny, with a high near 75.
Wednesday Night
Partly cloudy, with a low around 58.
Thursday
Mostly sunny, with a high near 76.
Thursday Night
Partly cloudy, with a low around 60.
Friday
Mostly sunny, with a high near 77.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Cool Valley MO
 38.73°N 90.31°W (Elev. 584 ft)
Last Update:
2:01 pm CDT Sep 18, 2026
Forecast Valid:
4pm CDT Sep 18, 2026-6pm CDT Sep 25, 2026
 
Forecast Discussion
 
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

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation