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.

Partly Cloudy

76°F

24°C

Humidity 85%
Wind Speed SE 7 mph
Barometer 29.87 in (1011.1 mb)
Dewpoint 71°F (22°C)
Visibility 10.00 mi
Heat Index77°F (25°C)
Last update 16 Jun 7:53 pm CDT
Extended Forecast for

O'Fallon IL

  • Tonight

    Tonight: Mostly cloudy, with a low around 68. Calm wind.

    Low: 68 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: Mostly cloudy, then gradually becoming sunny, with a high near 88. Calm wind becoming south around 6 mph in the afternoon.

    High: 88 °F

    Decreasing
    Clouds

  • Tuesday Night

    Tuesday Night: A slight chance of showers between 11pm and midnight. Partly cloudy, with a low around 72. South wind around 7 mph. Chance of precipitation is 20%.

    Low: 72 °F

    Slight Chance
    Showers then
    Partly Cloudy

  • Wednesday

    Wednesday: A chance of showers before 10am, then a chance of showers and thunderstorms between 10am and 1pm, then showers likely and possibly a thunderstorm after 1pm. Some of the storms could produce heavy rainfall. Partly sunny, with a high near 86. South wind 9 to 14 mph, with gusts as high as 22 mph. Chance of precipitation is 70%.

    High: 86 °F

    Chance
    Showers then
    Heavy Rain

  • Wednesday Night

    Wednesday Night: A 40 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 69. Southwest wind 6 to 10 mph.

    Low: 69 °F

    Chance
    T-storms

  • Juneteenth

    Juneteenth: Sunny, with a high near 85.

    High: 85 °F

    Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 68.

    Low: 68 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 91.

    High: 91 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 75.

    Low: 75 °F

    Mostly Clear

Detailed Forecast

Tonight
Mostly cloudy, with a low around 68. Calm wind.
Tuesday
Mostly cloudy, then gradually becoming sunny, with a high near 88. Calm wind becoming south around 6 mph in the afternoon.
Tuesday Night
A slight chance of showers between 11pm and midnight. Partly cloudy, with a low around 72. South wind around 7 mph. Chance of precipitation is 20%.
Wednesday
A chance of showers before 10am, then a chance of showers and thunderstorms between 10am and 1pm, then showers likely and possibly a thunderstorm after 1pm. Some of the storms could produce heavy rainfall. Partly sunny, with a high near 86. South wind 9 to 14 mph, with gusts as high as 22 mph. Chance of precipitation is 70%.
Wednesday Night
A 40 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 69. Southwest wind 6 to 10 mph.
Juneteenth
Sunny, with a high near 85.
Thursday Night
Mostly clear, with a low around 68.
Friday
Sunny, with a high near 91.
Friday Night
Mostly clear, with a low around 75.
Saturday
Sunny, with a high near 95.
Saturday Night
Mostly clear, with a low around 76.
Sunday
Sunny, with a high near 95.
Sunday Night
Mostly clear, with a low around 75.
Monday
A 20 percent chance of showers and thunderstorms. Sunny, with a high near 93.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
O'Fallon IL
 38.59°N 89.95°W (Elev. 545 ft)
Last Update:
6:07 pm CDT Jun 16, 2025
Forecast Valid:
9pm CDT Jun 16, 2025-6pm CDT Jun 23, 2025
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

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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