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.

Fair

63°F

17°C

Humidity 90%
Wind Speed S 5 mph
Barometer 29.85 in (1010.4 mb)
Dewpoint 60°F (16°C)
Visibility 10.00 mi
Last update 10 Mar 3:53 am CDT
Extended Forecast for

O'Fallon IL

  • Today

    Today: Increasing clouds, with a high near 82. South wind 7 to 16 mph, with gusts as high as 26 mph.

    High: 82 °F

    Increasing
    Clouds

  • Tonight

    Tonight: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 4am. Increasing clouds, with a low around 56. Southwest wind around 15 mph, with gusts as high as 31 mph. Chance of precipitation is 70%.

    Low: 56 °F

    Slight Chance
    T-storms then
    Showers
    Likely

  • Wednesday

    Wednesday: Showers and possibly a thunderstorm before 1pm, then a chance of showers. Temperature falling to around 50 by 5pm. Breezy, with a southwest wind 14 to 20 mph becoming northwest in the afternoon. Winds could gust as high as 31 mph. Chance of precipitation is 100%.

    High: 66 °F⇓

    Showers and
    Breezy

  • Wednesday Night

    Wednesday Night: Mostly cloudy, then gradually becoming mostly clear, with a low around 34. Breezy, with a northwest wind 15 to 20 mph decreasing to 7 to 12 mph after midnight. Winds could gust as high as 28 mph.

    Low: 34 °F

    Mostly Cloudy
    and Breezy
    then Partly
    Cloudy

  • Thursday

    Thursday: Sunny, with a high near 54. Light and variable wind becoming southwest 5 to 9 mph in the morning.

    High: 54 °F

    Sunny

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 45. Breezy.

    Low: 45 °F

    Partly Cloudy
    then Mostly
    Cloudy and
    Breezy

  • Friday

    Friday: Partly sunny, with a high near 63.

    High: 63 °F

    Partly Sunny

  • Friday Night

    Friday Night: Mostly cloudy, with a low around 40.

    Low: 40 °F

    Mostly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 67.

    High: 67 °F

    Mostly Sunny

Detailed Forecast

Today
Increasing clouds, with a high near 82. South wind 7 to 16 mph, with gusts as high as 26 mph.
Tonight
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 4am. Increasing clouds, with a low around 56. Southwest wind around 15 mph, with gusts as high as 31 mph. Chance of precipitation is 70%.
Wednesday
Showers and possibly a thunderstorm before 1pm, then a chance of showers. Temperature falling to around 50 by 5pm. Breezy, with a southwest wind 14 to 20 mph becoming northwest in the afternoon. Winds could gust as high as 31 mph. Chance of precipitation is 100%.
Wednesday Night
Mostly cloudy, then gradually becoming mostly clear, with a low around 34. Breezy, with a northwest wind 15 to 20 mph decreasing to 7 to 12 mph after midnight. Winds could gust as high as 28 mph.
Thursday
Sunny, with a high near 54. Light and variable wind becoming southwest 5 to 9 mph in the morning.
Thursday Night
Mostly cloudy, with a low around 45. Breezy.
Friday
Partly sunny, with a high near 63.
Friday Night
Mostly cloudy, with a low around 40.
Saturday
Mostly sunny, with a high near 67.
Saturday Night
A 20 percent chance of rain after 1am. Partly cloudy, with a low around 52.
Sunday
Rain likely. Mostly cloudy, with a high near 62. Breezy. Chance of precipitation is 70%.
Sunday Night
A chance of rain and snow. Mostly cloudy, with a low around 24. Blustery. Chance of precipitation is 30%.
Monday
Mostly sunny, with a high near 37.
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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:
3:46 am CDT Mar 10, 2026
Forecast Valid:
4am CDT Mar 10, 2026-6pm CDT Mar 16, 2026
 
Forecast Discussion
 
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Additional Resources

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Hourly Weather Forecast

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation