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

57°F

14°C

Humidity 22%
Wind Speed NE 7 mph
Barometer 30.02 in (1016.5 mb)
Dewpoint 18°F (-8°C)
Visibility 10.00 mi
Last update 16 Nov 1:53 pm CST
Extended Forecast for

O'Fallon IL

  • This Afternoon

    This Afternoon: Sunny, with a high near 59. North wind 3 to 7 mph.

    High: 59 °F

    Sunny

  • Tonight

    Tonight: Clear, with a low around 36. Light and variable wind.

    Low: 36 °F

    Clear

  • Monday

    Monday: A 20 percent chance of rain after 5pm. Increasing clouds, with a high near 60. Light east wind becoming southeast 6 to 11 mph in the morning. Winds could gust as high as 20 mph.

    High: 60 °F

    Sunny then
    Slight Chance
    Rain

  • Monday Night

    Monday Night: A chance of rain before 9pm, then a chance of rain and thunderstorms between 9pm and midnight, then rain and possibly a thunderstorm after midnight. Low around 48. Southeast wind 9 to 11 mph, with gusts as high as 21 mph. Chance of precipitation is 80%.

    Low: 48 °F

    Chance Rain
    then Rain

  • Tuesday

    Tuesday: A 30 percent chance of rain, mainly before noon. Partly sunny, with a high near 72. Southeast wind 7 to 9 mph becoming west in the afternoon.

    High: 72 °F

    Chance Rain

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 48.

    Low: 48 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: Mostly cloudy, with a high near 64.

    High: 64 °F

    Mostly Cloudy

  • Wednesday Night

    Wednesday Night: A 50 percent chance of rain. Mostly cloudy, with a low around 52.

    Low: 52 °F

    Chance Rain

  • Thursday

    Thursday: Rain and possibly a thunderstorm. High near 67. Chance of precipitation is 90%.

    High: 67 °F

    Rain

Detailed Forecast

This Afternoon
Sunny, with a high near 59. North wind 3 to 7 mph.
Tonight
Clear, with a low around 36. Light and variable wind.
Monday
A 20 percent chance of rain after 5pm. Increasing clouds, with a high near 60. Light east wind becoming southeast 6 to 11 mph in the morning. Winds could gust as high as 20 mph.
Monday Night
A chance of rain before 9pm, then a chance of rain and thunderstorms between 9pm and midnight, then rain and possibly a thunderstorm after midnight. Low around 48. Southeast wind 9 to 11 mph, with gusts as high as 21 mph. Chance of precipitation is 80%.
Tuesday
A 30 percent chance of rain, mainly before noon. Partly sunny, with a high near 72. Southeast wind 7 to 9 mph becoming west in the afternoon.
Tuesday Night
Mostly cloudy, with a low around 48.
Wednesday
Mostly cloudy, with a high near 64.
Wednesday Night
A 50 percent chance of rain. Mostly cloudy, with a low around 52.
Thursday
Rain and possibly a thunderstorm. High near 67. Chance of precipitation is 90%.
Thursday Night
Rain likely. Cloudy, with a low around 57. Chance of precipitation is 70%.
Friday
A 50 percent chance of rain. Partly sunny, with a high near 67.
Friday Night
A 30 percent chance of rain. Mostly cloudy, with a low around 45.
Saturday
Partly sunny, with a high near 56.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
O'Fallon IL
 38.59°N 89.92°W (Elev. 551 ft)
Last Update:
2:21 pm CST Nov 16, 2025
Forecast Valid:
2pm CST Nov 16, 2025-6pm CST Nov 22, 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