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

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

68°F

20°C

Humidity 59%
Wind Speed Vrbl 3 mph
Barometer 30.10 in (1019.0 mb)
Dewpoint 53°F (12°C)
Visibility 10.00 mi
Last update 10 Oct 10:53 am CDT
Extended Forecast for

O'Fallon IL

  • Today

    Today: Partly sunny, with a high near 80. East wind 5 to 8 mph.

    High: 80 °F

    Partly Sunny

  • Tonight

    Tonight: Mostly cloudy, with a low around 57. East wind 5 to 7 mph becoming calm in the evening.

    Low: 57 °F

    Mostly Cloudy

  • Sunday

    Sunday: Sunny, with a high near 86. Calm wind becoming west around 5 mph.

    High: 86 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 63. Calm wind becoming south around 5 mph in the evening.

    Low: 63 °F

    Mostly Clear

  • Columbus Day

    Columbus Day: Sunny, with a high near 93. Southwest wind 6 to 13 mph.

    High: 93 °F

    Sunny

  • Monday Night

    Monday Night: Clear, with a low around 70.

    Low: 70 °F

    Clear

  • Tuesday

    Tuesday: Sunny, with a high near 91.

    High: 91 °F

    Sunny

  • Tuesday Night

    Tuesday Night: A 30 percent chance of showers and thunderstorms, mainly after 1am. Mostly clear, with a low around 65.

    Low: 65 °F

    Slight Chance
    T-storms then
    Chance
    Showers

  • Wednesday

    Wednesday: Showers likely and possibly a thunderstorm. Mostly sunny, with a high near 81. Chance of precipitation is 60%.

    High: 81 °F

    Showers
    Likely

Detailed Forecast

Today
Partly sunny, with a high near 80. East wind 5 to 8 mph.
Tonight
Mostly cloudy, with a low around 57. East wind 5 to 7 mph becoming calm in the evening.
Sunday
Sunny, with a high near 86. Calm wind becoming west around 5 mph.
Sunday Night
Mostly clear, with a low around 63. Calm wind becoming south around 5 mph in the evening.
Columbus Day
Sunny, with a high near 93. Southwest wind 6 to 13 mph.
Monday Night
Clear, with a low around 70.
Tuesday
Sunny, with a high near 91.
Tuesday Night
A 30 percent chance of showers and thunderstorms, mainly after 1am. Mostly clear, with a low around 65.
Wednesday
Showers likely and possibly a thunderstorm. Mostly sunny, with a high near 81. Chance of precipitation is 60%.
Wednesday Night
A chance of showers, with thunderstorms also possible after 1am. Mostly cloudy, with a low around 61. Chance of precipitation is 40%.
Thursday
A 50 percent chance of showers and thunderstorms. Partly sunny, with a high near 79.
Thursday Night
A 30 percent chance of showers. Partly cloudy, with a low around 56.
Friday
A 20 percent chance of showers. Mostly sunny, with a high near 71.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
O'Fallon IL
 38.59°N 89.92°W (Elev. 551 ft)
Last Update:
8:36 am CDT Oct 10, 2026
Forecast Valid:
11am CDT Oct 10, 2026-6pm CDT Oct 16, 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