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.

Overcast

73°F

23°C

Humidity 94%
Wind Speed NE 3 mph
Barometer 30.02 in (1016.2 mb)
Dewpoint 71°F (22°C)
Visibility 10.00 mi
Last update 14 Jul 2:53 am CDT
Extended Forecast for

O'Fallon IL

  • Overnight

    Overnight: Mostly cloudy, with a low around 69. Calm wind.

    Low: 69 °F

    Mostly Cloudy

  • Monday

    Monday: A 20 percent chance of showers and thunderstorms after 2pm. Mostly cloudy, with a high near 86. East wind 3 to 5 mph.

    High: 86 °F

    Mostly Cloudy
    then Slight
    Chance
    T-storms

  • Monday Night

    Monday Night: Mostly cloudy, with a low around 71. East wind around 5 mph becoming calm in the evening.

    Low: 71 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: A 50 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 87. Calm wind becoming south around 6 mph in the morning.

    High: 87 °F

    Slight Chance
    T-storms then
    Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A 20 percent chance of showers and thunderstorms before 1am. Partly cloudy, with a low around 73. Southwest wind around 5 mph becoming calm in the evening.

    Low: 73 °F

    Slight Chance
    T-storms

  • Wednesday

    Wednesday: A 30 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 93.

    High: 93 °F

    Mostly Sunny
    then Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A 20 percent chance of showers and thunderstorms before 1am. Partly cloudy, with a low around 75.

    Low: 75 °F

    Slight Chance
    T-storms

  • Thursday

    Thursday: A 40 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 93.

    High: 93 °F

    Sunny then
    Chance
    T-storms

  • Thursday Night

    Thursday Night: A 30 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 74.

    Low: 74 °F

    Chance
    T-storms

Detailed Forecast

Overnight
Mostly cloudy, with a low around 69. Calm wind.
Monday
A 20 percent chance of showers and thunderstorms after 2pm. Mostly cloudy, with a high near 86. East wind 3 to 5 mph.
Monday Night
Mostly cloudy, with a low around 71. East wind around 5 mph becoming calm in the evening.
Tuesday
A 50 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 87. Calm wind becoming south around 6 mph in the morning.
Tuesday Night
A 20 percent chance of showers and thunderstorms before 1am. Partly cloudy, with a low around 73. Southwest wind around 5 mph becoming calm in the evening.
Wednesday
A 30 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 93.
Wednesday Night
A 20 percent chance of showers and thunderstorms before 1am. Partly cloudy, with a low around 75.
Thursday
A 40 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 93.
Thursday Night
A 30 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 74.
Friday
A 40 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 90.
Friday Night
A 20 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 74.
Saturday
A 30 percent chance of showers and thunderstorms. Partly sunny, with a high near 90.
Saturday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 73.
Sunday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 92.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
O'Fallon IL
 38.59°N 89.92°W (Elev. 551 ft)
Last Update:
1:51 am CDT Jul 14, 2025
Forecast Valid:
3am CDT Jul 14, 2025-6pm CDT Jul 20, 2025
 
Forecast Discussion
 
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Additional Resources

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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