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

68°F

20°C

Humidity 78%
Wind Speed Calm
Barometer 29.99 in (1015.3 mb)
Dewpoint 61°F (16°C)
Visibility 10.00 mi
Last update 20 Jun 12:53 am CDT
Extended Forecast for

O'Fallon IL

Flood Watch June 21, 07:00am until June 22, 07:00am
Click here for hazard details and duration
Flood Watch

  • Overnight

    Overnight: Mostly cloudy, with a low around 66. Light southwest wind.

    Low: 66 °F

    Mostly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 86. Calm wind becoming north around 5 mph.

    High: 86 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 67. Calm wind becoming southeast around 6 mph after midnight.

    Low: 67 °F

    Partly Cloudy

  • Sunday

    Sunday: Showers and thunderstorms before 3pm, then showers and possibly a thunderstorm, mainly after 3pm. High near 84. Southeast wind 8 to 18 mph becoming south in the afternoon. Winds could gust as high as 29 mph. Chance of precipitation is 80%.

    High: 84 °F

    T-storms

  • Sunday Night

    Sunday Night: Showers and possibly a thunderstorm before 1am, then a chance of showers. Low around 66. Southwest wind 9 to 14 mph becoming northwest after midnight. Winds could gust as high as 21 mph. Chance of precipitation is 90%.

    Low: 66 °F

    T-storms then
    Showers

  • Monday

    Monday: A 20 percent chance of showers. Mostly cloudy, with a high near 78.

    High: 78 °F

    Slight Chance
    Showers

  • Monday Night

    Monday Night: Partly cloudy, with a low around 61.

    Low: 61 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 81.

    High: 81 °F

    Mostly Sunny

  • Tuesday Night

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

    Low: 63 °F

    Mostly Clear

Detailed Forecast

Overnight
Mostly cloudy, with a low around 66. Light southwest wind.
Saturday
Mostly sunny, with a high near 86. Calm wind becoming north around 5 mph.
Saturday Night
Partly cloudy, with a low around 67. Calm wind becoming southeast around 6 mph after midnight.
Sunday
Showers and thunderstorms before 3pm, then showers and possibly a thunderstorm, mainly after 3pm. High near 84. Southeast wind 8 to 18 mph becoming south in the afternoon. Winds could gust as high as 29 mph. Chance of precipitation is 80%.
Sunday Night
Showers and possibly a thunderstorm before 1am, then a chance of showers. Low around 66. Southwest wind 9 to 14 mph becoming northwest after midnight. Winds could gust as high as 21 mph. Chance of precipitation is 90%.
Monday
A 20 percent chance of showers. Mostly cloudy, with a high near 78.
Monday Night
Partly cloudy, with a low around 61.
Tuesday
Mostly sunny, with a high near 81.
Tuesday Night
Mostly clear, with a low around 63.
Wednesday
Mostly sunny, with a high near 83.
Wednesday Night
Mostly clear, with a low around 64.
Thursday
A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 82.
Thursday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 63.
Friday
A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 82.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
O'Fallon IL
 38.59°N 89.92°W (Elev. 551 ft)
Last Update:
1:26 am CDT Jun 20, 2026
Forecast Valid:
1am CDT Jun 20, 2026-6pm CDT Jun 26, 2026
 
Forecast Discussion
 
Get as KML Get as XML

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