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

Hazardous Weather Conditions

Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

A Few Clouds

79°F

26°C

Humidity 85%
Wind Speed SE 3 mph
Barometer 30.02 in (1016.0 mb)
Dewpoint 74°F (23°C)
Visibility 10.00 mi
Heat Index83°F (28°C)
Last update 14 Jul 8:53 pm CDT
Extended Forecast for

O'Fallon IL

  • Tonight

    Tonight: Patchy fog after 3am. Otherwise, increasing clouds, with a low around 71. Light southeast wind.

    Low: 71 °F

    Partly Cloudy
    then Patchy
    Fog

  • Tuesday

    Tuesday: A slight chance of showers, then a chance of showers and thunderstorms after 10am. Patchy fog before 8am. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 86. Calm wind becoming south around 6 mph in the morning. Chance of precipitation is 50%.

    High: 86 °F

    Slight Chance
    T-storms and
    Patchy Fog
    then Chance
    T-storms

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 73. South wind around 5 mph becoming calm after midnight.

    Low: 73 °F

    Partly Cloudy

  • Wednesday

    Wednesday: A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 92. Heat index values as high as 102. Southwest wind 3 to 7 mph.

    High: 92 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 75. Southwest wind around 6 mph.

    Low: 75 °F

    Slight Chance
    T-storms

  • Thursday

    Thursday: A 40 percent chance of showers and thunderstorms, mainly after 1pm. Mostly sunny, with a high near 92.

    High: 92 °F

    Chance
    T-storms

  • Thursday Night

    Thursday Night: A 40 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 72.

    Low: 72 °F

    Chance
    T-storms

  • Friday

    Friday: A 30 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 89.

    High: 89 °F

    Chance
    T-storms

  • Friday Night

    Friday Night: A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 74.

    Low: 74 °F

    Slight Chance
    T-storms

Detailed Forecast

Tonight
Patchy fog after 3am. Otherwise, increasing clouds, with a low around 71. Light southeast wind.
Tuesday
A slight chance of showers, then a chance of showers and thunderstorms after 10am. Patchy fog before 8am. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 86. Calm wind becoming south around 6 mph in the morning. Chance of precipitation is 50%.
Tuesday Night
Partly cloudy, with a low around 73. South wind around 5 mph becoming calm after midnight.
Wednesday
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 92. Heat index values as high as 102. Southwest wind 3 to 7 mph.
Wednesday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 75. Southwest wind around 6 mph.
Thursday
A 40 percent chance of showers and thunderstorms, mainly after 1pm. Mostly sunny, with a high near 92.
Thursday Night
A 40 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 72.
Friday
A 30 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 89.
Friday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 74.
Saturday
A 30 percent chance of showers and thunderstorms, mainly after 1pm. Mostly sunny, with a high near 92.
Saturday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 75.
Sunday
A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 94.
Sunday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 74.
Monday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 92.
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ABOUT THIS FORECAST

 
Point Forecast:
O'Fallon IL
 38.59°N 89.92°W (Elev. 551 ft)
Last Update:
8:52 pm CDT Jul 14, 2025
Forecast Valid:
9pm CDT Jul 14, 2025-6pm CDT Jul 21, 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