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

Hazardous Weather Conditions

Current conditions at

St. Louis Lambert International Airport (KSTL)

Lat: 38.75°NLon: 90.37°WElev: 604ft.

Mostly Cloudy

84°F

29°C

Humidity 65%
Wind Speed NW 5 mph
Barometer 29.98 in (1013.8 mb)
Dewpoint 71°F (22°C)
Visibility 10.00 mi
Heat Index89°F (32°C)
Last update 18 Aug 7:51 pm CDT
Extended Forecast for

Florissant MO

Heat Advisory August 18, 08:23pm until August 19, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 18, 08:23pm until August 19, 08:00pm

    NOW until 8:00pm Tue

    Heat Advisory

  • Tonight

    Low: 77 °F

    Chance
    T-storms

  • Tuesday

    Tuesday: A slight chance of showers and thunderstorms before 9am, then a slight chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 94. Heat index values as high as 103. Light and variable wind becoming northwest 5 to 8 mph in the morning. Chance of precipitation is 20%.

    High: 94 °F

    Slight Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A chance of showers and thunderstorms before 1am, then a slight chance of showers. Partly cloudy, with a low around 74. North wind 3 to 7 mph. Chance of precipitation is 40%.

    Low: 74 °F

    Chance
    T-storms then
    Chance
    Showers

  • Wednesday

    Wednesday: A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 88. Northeast wind 5 to 9 mph.

    High: 88 °F

    Partly Sunny
    then Slight
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 68. Northeast wind 6 to 8 mph.

    Low: 68 °F

    Mostly Clear

  • Thursday

    Thursday: Mostly sunny, with a high near 87.

    High: 87 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 69.

    Low: 69 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 89.

    High: 89 °F

    Sunny

Detailed Forecast

Tonight
A 30 percent chance of showers and thunderstorms, mainly after 5am. Partly cloudy, with a low around 77. South wind 3 to 5 mph.
Tuesday
A slight chance of showers and thunderstorms before 9am, then a slight chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 94. Heat index values as high as 103. Light and variable wind becoming northwest 5 to 8 mph in the morning. Chance of precipitation is 20%.
Tuesday Night
A chance of showers and thunderstorms before 1am, then a slight chance of showers. Partly cloudy, with a low around 74. North wind 3 to 7 mph. Chance of precipitation is 40%.
Wednesday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 88. Northeast wind 5 to 9 mph.
Wednesday Night
Mostly clear, with a low around 68. Northeast wind 6 to 8 mph.
Thursday
Mostly sunny, with a high near 87.
Thursday Night
Mostly clear, with a low around 69.
Friday
Sunny, with a high near 89.
Friday Night
Mostly clear, with a low around 70.
Saturday
Mostly sunny, with a high near 87.
Saturday Night
Mostly clear, with a low around 64.
Sunday
Sunny, with a high near 81.
Sunday Night
Partly cloudy, with a low around 60.
Monday
Mostly sunny, with a high near 78.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Florissant MO
 38.78°N 90.34°W (Elev. 528 ft)
Last Update:
8:16 pm CDT Aug 18, 2025
Forecast Valid:
8pm CDT Aug 18, 2025-6pm CDT Aug 25, 2025
 
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