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

77°F

25°C

Humidity 54%
Wind Speed SW 12 G 17 mph
Barometer 29.67 in (1004.5 mb)
Dewpoint 59°F (15°C)
Visibility 10.00 mi
Heat Index79°F (26°C)
Last update 15 Nov 11:53 am CST
Extended Forecast for

O'Fallon IL

  • This Afternoon

    This Afternoon: Sunny, with a high near 79. West wind 10 to 14 mph, with gusts as high as 24 mph.

    High: 79 °F

    Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 43. North wind 8 to 11 mph, with gusts as high as 21 mph.

    Low: 43 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 59. North wind 5 to 9 mph.

    High: 59 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 34. Light and variable wind.

    Low: 34 °F

    Mostly Clear

  • Monday

    Monday: A 20 percent chance of showers after noon. Mostly sunny, with a high near 58. Light east wind becoming southeast 6 to 11 mph in the morning.

    High: 58 °F

    Sunny then
    Slight Chance
    Showers

  • Monday Night

    Monday Night: Showers and possibly a thunderstorm before 3am, then showers likely. Low around 47. Chance of precipitation is 80%.

    Low: 47 °F

    Showers

  • Tuesday

    Tuesday: Partly sunny, with a high near 67.

    High: 67 °F

    Partly Sunny

  • Tuesday Night

    Tuesday Night: A 20 percent chance of rain after midnight. Mostly cloudy, with a low around 45.

    Low: 45 °F

    Mostly Cloudy
    then Slight
    Chance Rain

  • Wednesday

    Wednesday: A 30 percent chance of rain, mainly after noon. Partly sunny, with a high near 61.

    High: 61 °F

    Chance Rain

Detailed Forecast

This Afternoon
Sunny, with a high near 79. West wind 10 to 14 mph, with gusts as high as 24 mph.
Tonight
Mostly clear, with a low around 43. North wind 8 to 11 mph, with gusts as high as 21 mph.
Sunday
Sunny, with a high near 59. North wind 5 to 9 mph.
Sunday Night
Mostly clear, with a low around 34. Light and variable wind.
Monday
A 20 percent chance of showers after noon. Mostly sunny, with a high near 58. Light east wind becoming southeast 6 to 11 mph in the morning.
Monday Night
Showers and possibly a thunderstorm before 3am, then showers likely. Low around 47. Chance of precipitation is 80%.
Tuesday
Partly sunny, with a high near 67.
Tuesday Night
A 20 percent chance of rain after midnight. Mostly cloudy, with a low around 45.
Wednesday
A 30 percent chance of rain, mainly after noon. Partly sunny, with a high near 61.
Wednesday Night
Rain likely, mainly after midnight. Mostly cloudy, with a low around 50. Chance of precipitation is 60%.
Thursday
Rain and possibly a thunderstorm. High near 63. Chance of precipitation is 80%.
Thursday Night
Rain likely. Mostly cloudy, with a low around 52. Chance of precipitation is 70%.
Friday
A 40 percent chance of rain. Mostly cloudy, with a high near 64.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
O'Fallon IL
 38.59°N 89.92°W (Elev. 551 ft)
Last Update:
10:42 am CST Nov 15, 2025
Forecast Valid:
12pm CST Nov 15, 2025-6pm CST Nov 21, 2025
 
Forecast Discussion
 
Get as KML Get as XML

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