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.

Fair

81°F

27°C

Humidity 65%
Wind Speed SW 6 mph
Barometer 29.97 in (1013.2 mb)
Dewpoint 68°F (20°C)
Visibility 10.00 mi
Heat Index84°F (29°C)
Last update 19 Sep 2:51 am CDT
Extended Forecast for

Lambert-St. Louis International Airport MO

Heat Advisory September 19, 03:25am until September 19, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory September 19, 03:25am until September 19, 08:00pm

    NOW until 8:00pm Sat

    Heat Advisory

  • Overnight

    Low: 77 °F

    Mostly Clear

  • Saturday

    Saturday: Partly sunny and hot, with a high near 97. Southwest wind 7 to 10 mph.

    High: 97 °F

    Hot

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 75. South wind 6 to 9 mph becoming west after midnight.

    Low: 75 °F

    Partly Cloudy

  • Sunday

    Sunday: A slight chance of showers before 10am, then a slight chance of showers and thunderstorms after 4pm. Partly sunny, with a high near 91. Northwest wind 6 to 8 mph. Chance of precipitation is 20%.

    High: 91 °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 68. Northeast wind 9 to 13 mph. Chance of precipitation is 70%.

    Low: 68 °F

    Chance
    T-storms then
    Showers
    Likely

  • Monday

    Monday: Showers likely and possibly a thunderstorm before 10am, then showers likely between 10am and 1pm, then a chance of showers and thunderstorms after 1pm. Mostly cloudy, with a high near 76. Chance of precipitation is 70%.

    High: 76 °F

    Showers
    Likely

  • Monday Night

    Monday Night: A 20 percent chance of showers. Mostly cloudy, with a low around 60.

    Low: 60 °F

    Slight Chance
    Showers

  • Tuesday

    Tuesday: Partly sunny, with a high near 70.

    High: 70 °F

    Partly Sunny

Detailed Forecast

Overnight
Mostly clear, with a low around 77. South wind around 6 mph.
Saturday
Partly sunny and hot, with a high near 97. Southwest wind 7 to 10 mph.
Saturday Night
Partly cloudy, with a low around 75. South wind 6 to 9 mph becoming west after midnight.
Sunday
A slight chance of showers before 10am, then a slight chance of showers and thunderstorms after 4pm. Partly sunny, with a high near 91. Northwest wind 6 to 8 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 68. Northeast wind 9 to 13 mph. Chance of precipitation is 70%.
Monday
Showers likely and possibly a thunderstorm before 10am, then showers likely between 10am and 1pm, then a chance of showers and thunderstorms after 1pm. Mostly cloudy, with a high near 76. Chance of precipitation is 70%.
Monday Night
A 20 percent chance of showers. Mostly cloudy, with a low around 60.
Tuesday
Partly sunny, with a high near 70.
Tuesday Night
Mostly cloudy, with a low around 56.
Wednesday
Mostly sunny, with a high near 74.
Wednesday Night
Partly cloudy, with a low around 57.
Thursday
Mostly sunny, with a high near 76.
Thursday Night
Mostly cloudy, with a low around 59.
Friday
Partly sunny, with a high near 78.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Lambert-St. Louis International Airport MO
 38.76°N 90.37°W (Elev. 551 ft)
Last Update:
1:26 am CDT Sep 19, 2026
Forecast Valid:
3am CDT Sep 19, 2026-6pm CDT Sep 25, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

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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