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Hazardous Weather Conditions

Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

79°F

26°C

Humidity 90%
Wind Speed SW 3 mph
Barometer 30.03 in (1016.4 mb)
Dewpoint 76°F (24°C)
Visibility 10.00 mi
Heat Index83°F (28°C)
Last update 16 Aug 9:53 pm CDT
Extended Forecast for

O'Fallon IL

Heat Advisory August 16, 10:16pm until August 18, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 16, 10:16pm until August 18, 08:00pm

    NOW until 8:00pm Mon

    Heat Advisory

  • Tonight

    Low: 75 °F

    Partly Cloudy

  • Sunday

    Sunday: A 30 percent chance of showers and thunderstorms, mainly after 5pm. Mostly sunny and hot, with a high near 98. Heat index values as high as 109. Calm wind becoming west around 5 mph in the afternoon.

    High: 98 °F

    Sunny then
    Chance
    T-storms

  • Sunday Night

    Sunday Night: A 30 percent chance of showers and thunderstorms, mainly before 7pm. Partly cloudy, with a low around 75. Light and variable wind.

    Low: 75 °F

    Chance
    T-storms then
    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 96. Heat index values as high as 107. Calm wind becoming south around 5 mph in the afternoon.

    High: 96 °F

    Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 76. Light and variable wind.

    Low: 76 °F

    Mostly Clear

  • Tuesday

    Tuesday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 95.

    High: 95 °F

    Sunny then
    Slight Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A 30 percent chance of showers and thunderstorms, mainly before 1am. Partly cloudy, with a low around 72.

    Low: 72 °F

    Chance
    T-storms

  • Wednesday

    Wednesday: A slight chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 84. Chance of precipitation is 20%.

    High: 84 °F

    Slight Chance
    Showers then
    Slight Chance
    T-storms

Detailed Forecast

Tonight
Partly cloudy, with a low around 75. Calm wind.
Sunday
A 30 percent chance of showers and thunderstorms, mainly after 5pm. Mostly sunny and hot, with a high near 98. Heat index values as high as 109. Calm wind becoming west around 5 mph in the afternoon.
Sunday Night
A 30 percent chance of showers and thunderstorms, mainly before 7pm. Partly cloudy, with a low around 75. Light and variable wind.
Monday
Sunny, with a high near 96. Heat index values as high as 107. Calm wind becoming south around 5 mph in the afternoon.
Monday Night
Mostly clear, with a low around 76. Light and variable wind.
Tuesday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 95.
Tuesday Night
A 30 percent chance of showers and thunderstorms, mainly before 1am. Partly cloudy, with a low around 72.
Wednesday
A slight chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 84. Chance of precipitation is 20%.
Wednesday Night
Partly cloudy, with a low around 68.
Thursday
Mostly sunny, with a high near 84.
Thursday Night
Mostly clear, with a low around 65.
Friday
Sunny, with a high near 87.
Friday Night
Mostly clear, with a low around 66.
Saturday
Sunny, with a high near 89.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
O'Fallon IL
 38.59°N 89.95°W (Elev. 545 ft)
Last Update:
5:56 pm CDT Aug 16, 2025
Forecast Valid:
10pm CDT Aug 16, 2025-6pm CDT Aug 23, 2025
 
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