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.

Overcast

83°F

28°C

Humidity 49%
Wind Speed E 14 mph
Barometer 30.09 in (1018.5 mb)
Dewpoint 62°F (17°C)
Visibility 10.00 mi
Heat Index84°F (29°C)
Last update 30 Aug 2:53 pm CDT
Extended Forecast for

O'Fallon IL

  • This Afternoon

    This Afternoon: A 20 percent chance of showers. Mostly sunny, with a high near 84. East wind around 6 mph.

    High: 84 °F

    Slight Chance
    Showers

  • Tonight

    Tonight: Mostly cloudy, with a low around 62. East wind 3 to 6 mph.

    Low: 62 °F

    Mostly Cloudy

  • Sunday

    Sunday: Mostly sunny, with a high near 82. East wind 3 to 8 mph.

    High: 82 °F

    Mostly Sunny

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 56. Northeast wind 3 to 6 mph.

    Low: 56 °F

    Mostly Cloudy

  • Labor Day

    Labor Day: Partly sunny, with a high near 81. East wind 3 to 6 mph.

    High: 81 °F

    Partly Sunny

  • Monday Night

    Monday Night: Mostly cloudy, with a low around 58.

    Low: 58 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: A slight chance of showers before 1pm, then a slight chance of showers and thunderstorms between 1pm and 4pm, then a slight chance of showers after 4pm. Partly sunny, with a high near 80. Chance of precipitation is 20%.

    High: 80 °F

    Slight Chance
    Showers then
    Slight Chance
    T-storms

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 58.

    Low: 58 °F

    Partly Cloudy

  • Wednesday

    Wednesday: A 30 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 83.

    High: 83 °F

    Sunny then
    Chance
    Showers

Detailed Forecast

This Afternoon
A 20 percent chance of showers. Mostly sunny, with a high near 84. East wind around 6 mph.
Tonight
Mostly cloudy, with a low around 62. East wind 3 to 6 mph.
Sunday
Mostly sunny, with a high near 82. East wind 3 to 8 mph.
Sunday Night
Mostly cloudy, with a low around 56. Northeast wind 3 to 6 mph.
Labor Day
Partly sunny, with a high near 81. East wind 3 to 6 mph.
Monday Night
Mostly cloudy, with a low around 58.
Tuesday
A slight chance of showers before 1pm, then a slight chance of showers and thunderstorms between 1pm and 4pm, then a slight chance of showers after 4pm. Partly sunny, with a high near 80. Chance of precipitation is 20%.
Tuesday Night
Partly cloudy, with a low around 58.
Wednesday
A 30 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 83.
Wednesday Night
A 20 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 50.
Thursday
Sunny, with a high near 70.
Thursday Night
Partly cloudy, with a low around 48.
Friday
Sunny, with a high near 75.
Friday Night
Mostly clear, with a low around 51.
Saturday
Sunny, with a high near 80.
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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:
2:15 pm CDT Aug 30, 2025
Forecast Valid:
3pm CDT Aug 30, 2025-6pm CDT Sep 6, 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