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

81°F

27°C

Humidity 32%
Wind Speed S 10 mph
Barometer 29.87 in (1011.3 mb)
Dewpoint 48°F (9°C)
Visibility 10.00 mi
Heat Index80°F (27°C)
Last update 25 Mar 4:53 pm CDT
Extended Forecast for

O'Fallon IL

  • Tonight

    Tonight: Mostly clear, with a low around 63. South wind 9 to 11 mph, with gusts as high as 21 mph.

    Low: 63 °F

    Mostly Clear

  • Thursday

    Thursday: Sunny, with a high near 90. Southwest wind 10 to 16 mph, with gusts as high as 26 mph.

    High: 90 °F

    Sunny

  • Thursday Night

    Thursday Night: A chance of rain and thunderstorms before 1am, then rain and possibly a thunderstorm between 1am and 4am, then rain after 4am. Low around 44. Southwest wind 13 to 18 mph becoming north after midnight. Winds could gust as high as 28 mph. Chance of precipitation is 90%.

    Low: 44 °F

    Chance
    T-storms then
    Rain

  • Friday

    Friday: A 40 percent chance of rain before 1pm. Cloudy, then gradually becoming mostly sunny, with a high near 52. North wind 16 to 18 mph, with gusts as high as 28 mph.

    High: 52 °F

    Chance Rain

  • Friday Night

    Friday Night: Mostly clear, with a low around 32. North wind 6 to 13 mph, with gusts as high as 21 mph.

    Low: 32 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 56.

    High: 56 °F

    Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 41.

    Low: 41 °F

    Partly Cloudy

  • Sunday

    Sunday: Partly sunny, with a high near 63.

    High: 63 °F

    Partly Sunny

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 54.

    Low: 54 °F

    Mostly Cloudy

Detailed Forecast

Tonight
Mostly clear, with a low around 63. South wind 9 to 11 mph, with gusts as high as 21 mph.
Thursday
Sunny, with a high near 90. Southwest wind 10 to 16 mph, with gusts as high as 26 mph.
Thursday Night
A chance of rain and thunderstorms before 1am, then rain and possibly a thunderstorm between 1am and 4am, then rain after 4am. Low around 44. Southwest wind 13 to 18 mph becoming north after midnight. Winds could gust as high as 28 mph. Chance of precipitation is 90%.
Friday
A 40 percent chance of rain before 1pm. Cloudy, then gradually becoming mostly sunny, with a high near 52. North wind 16 to 18 mph, with gusts as high as 28 mph.
Friday Night
Mostly clear, with a low around 32. North wind 6 to 13 mph, with gusts as high as 21 mph.
Saturday
Sunny, with a high near 56.
Saturday Night
Partly cloudy, with a low around 41.
Sunday
Partly sunny, with a high near 63.
Sunday Night
Mostly cloudy, with a low around 54.
Monday
A 20 percent chance of rain and thunderstorms before 1pm. Mostly sunny, with a high near 78.
Monday Night
A 30 percent chance of rain. Mostly cloudy, with a low around 61.
Tuesday
A 40 percent chance of rain and thunderstorms. Partly sunny, with a high near 80.
Tuesday Night
A 40 percent chance of rain and thunderstorms. Mostly cloudy, with a low around 63.
Wednesday
A 40 percent chance of rain and thunderstorms. Partly sunny, with a high near 78.
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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:
4:31 pm CDT Mar 25, 2026
Forecast Valid:
5pm CDT Mar 25, 2026-6pm CDT Apr 1, 2026
 
Forecast Discussion
 
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Additional Resources

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High Temperature

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Chance of Precipitation