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

Lowell to Impact Hawaii; Heat Persists in the South-Central U.S.

Hurricane Lowell is forecast to pass west of Kauai`s coastal waters tonight. Impacts such as high surf and heavy rain could impact all of the islands. Sweltering heat remains across the South-Central Plains and Lower/Middle Mississippi Valley into this week with limited nighttime relief. Periods of moderate to heavy rainfall will be possible through Tuesday morning in the northern Rockies. Read More >

Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

68°F

20°C

Humidity 76%
Wind Speed E 5 mph
Barometer 30.10 in (1018.8 mb)
Dewpoint 60°F (16°C)
Visibility 10.00 mi
Last update 7 Sep 7:53 am CDT
Extended Forecast for

O'Fallon IL

  • Labor Day

    Labor Day: Partly sunny, then gradually becoming sunny, with a high near 88. Light southeast wind becoming east 5 to 9 mph in the morning.

    High: 88 °F

    Becoming
    Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 61. East wind 3 to 6 mph.

    Low: 61 °F

    Mostly Clear

  • Tuesday

    Tuesday: Mostly sunny, with a high near 95. South wind 3 to 7 mph.

    High: 95 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 71. South wind 5 to 9 mph.

    Low: 71 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Sunny and hot, with a high near 98. Southwest wind 8 to 11 mph.

    High: 98 °F

    Hot

  • Wednesday Night

    Wednesday Night: Showers and possibly a thunderstorm. Low around 71. Chance of precipitation is 90%.

    Low: 71 °F

    Showers
    Likely then
    Showers

  • Thursday

    Thursday: A 50 percent chance of showers and thunderstorms before 1pm. Partly sunny, with a high near 84.

    High: 84 °F

    Chance
    Showers

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 63.

    Low: 63 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 87.

    High: 87 °F

    Sunny

Detailed Forecast

Labor Day
Partly sunny, then gradually becoming sunny, with a high near 88. Light southeast wind becoming east 5 to 9 mph in the morning.
Tonight
Mostly clear, with a low around 61. East wind 3 to 6 mph.
Tuesday
Mostly sunny, with a high near 95. South wind 3 to 7 mph.
Tuesday Night
Partly cloudy, with a low around 71. South wind 5 to 9 mph.
Wednesday
Sunny and hot, with a high near 98. Southwest wind 8 to 11 mph.
Wednesday Night
Showers and possibly a thunderstorm. Low around 71. Chance of precipitation is 90%.
Thursday
A 50 percent chance of showers and thunderstorms before 1pm. Partly sunny, with a high near 84.
Thursday Night
Mostly clear, with a low around 63.
Friday
Sunny, with a high near 87.
Friday Night
A 30 percent chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 67.
Saturday
A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 91.
Saturday Night
Mostly clear, with a low around 68.
Sunday
A 20 percent chance of showers. Sunny, with a high near 91.
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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:
8:11 am CDT Sep 7, 2026
Forecast Valid:
8am CDT Sep 7, 2026-6pm CDT Sep 13, 2026
 
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