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, Spirit Of St. Louis Airport (KSUS)

Lat: 38.66°NLon: 90.66°WElev: 463ft.

Fair

74°F

23°C

Humidity 82%
Wind Speed Calm
Barometer 29.94 in (1012.7 mb)
Dewpoint 68°F (20°C)
Visibility 10.00 mi
Last update 19 Sep 3:54 am CDT
Extended Forecast for

Saint Peters MO

Heat Advisory September 19, 03:59am until September 19, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory September 19, 03:59am until September 19, 08:00pm

    NOW until 8:00pm Sat

    Heat Advisory

  • Overnight

    Low: 74 °F

    Mostly Clear

  • Saturday

    Saturday: Partly sunny and hot, with a high near 97. Heat index values as high as 100. Southwest wind 5 to 7 mph.

    High: 97 °F

    Hot

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 73. Calm wind becoming southwest around 5 mph after midnight.

    Low: 73 °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. Calm wind becoming northwest around 5 mph in the afternoon. 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 67. Northeast wind around 7 mph. Chance of precipitation is 70%.

    Low: 67 °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 77. Chance of precipitation is 60%.

    High: 77 °F

    Showers
    Likely

  • Monday Night

    Monday Night: A 20 percent chance of showers. Mostly cloudy, with a low around 59.

    Low: 59 °F

    Slight Chance
    Showers

  • Tuesday

    Tuesday: Mostly cloudy, with a high near 70.

    High: 70 °F

    Mostly Cloudy

Detailed Forecast

Overnight
Mostly clear, with a low around 74. South wind 3 to 5 mph.
Saturday
Partly sunny and hot, with a high near 97. Heat index values as high as 100. Southwest wind 5 to 7 mph.
Saturday Night
Partly cloudy, with a low around 73. Calm wind becoming southwest around 5 mph 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. Calm wind becoming northwest around 5 mph in the afternoon. 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 67. Northeast wind around 7 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 77. Chance of precipitation is 60%.
Monday Night
A 20 percent chance of showers. Mostly cloudy, with a low around 59.
Tuesday
Mostly cloudy, with a high near 70.
Tuesday Night
Mostly cloudy, with a low around 54.
Wednesday
Mostly sunny, with a high near 73.
Wednesday Night
Partly cloudy, with a low around 56.
Thursday
Mostly sunny, with a high near 76.
Thursday Night
Mostly cloudy, with a low around 58.
Friday
Partly sunny, with a high near 77.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Saint Peters MO
 38.78°N 90.59°W (Elev. 492 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

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