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

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

66°F

19°C

Humidity 78%
Wind Speed Calm
Barometer 30.15 in (1020.8 mb)
Dewpoint 59°F (15°C)
Visibility 10.00 mi
Last update 23 Jun 10:53 pm CDT
Extended Forecast for

Collinsville IL

  • Tonight

    Tonight: Partly cloudy, with a low around 63. Light southeast wind.

    Low: 63 °F

    Partly Cloudy

  • Wednesday

    Wednesday: A 20 percent chance of showers and thunderstorms after 3pm. Partly sunny, with a high near 84. South wind 5 to 7 mph.

    High: 84 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A chance of showers and thunderstorms. Partly cloudy, with a low around 68. South wind around 6 mph becoming calm in the evening. Chance of precipitation is 40%.

    Low: 68 °F

    Slight Chance
    T-storms then
    Chance
    Showers

  • Thursday

    Thursday: A slight chance of showers before 1pm, then showers likely and possibly a thunderstorm between 1pm and 4pm, then showers and thunderstorms likely after 4pm. Patchy fog before 8am. Otherwise, partly sunny, with a high near 85. Calm wind becoming south around 5 mph. Chance of precipitation is 70%.

    High: 85 °F

    Patchy Fog
    then T-storms
    Likely

  • Thursday Night

    Thursday Night: Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 68. East wind 3 to 5 mph. Chance of precipitation is 90%.

    Low: 68 °F

    Heavy Rain

  • Friday

    Friday: Showers and possibly a thunderstorm before 1pm, then showers and thunderstorms likely after 1pm. High near 82. Chance of precipitation is 80%.

    High: 82 °F

    Showers then
    T-storms

  • Friday Night

    Friday Night: Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 72. Chance of precipitation is 60%.

    Low: 72 °F

    Showers
    Likely

  • Saturday

    Saturday: A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 89.

    High: 89 °F

    Chance
    Showers then
    Chance
    T-storms

  • Saturday Night

    Saturday Night: A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 75.

    Low: 75 °F

    Slight Chance
    T-storms

Detailed Forecast

Tonight
Partly cloudy, with a low around 63. Light southeast wind.
Wednesday
A 20 percent chance of showers and thunderstorms after 3pm. Partly sunny, with a high near 84. South wind 5 to 7 mph.
Wednesday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 68. South wind around 6 mph becoming calm in the evening. Chance of precipitation is 40%.
Thursday
A slight chance of showers before 1pm, then showers likely and possibly a thunderstorm between 1pm and 4pm, then showers and thunderstorms likely after 4pm. Patchy fog before 8am. Otherwise, partly sunny, with a high near 85. Calm wind becoming south around 5 mph. Chance of precipitation is 70%.
Thursday Night
Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 68. East wind 3 to 5 mph. Chance of precipitation is 90%.
Friday
Showers and possibly a thunderstorm before 1pm, then showers and thunderstorms likely after 1pm. High near 82. Chance of precipitation is 80%.
Friday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 72. Chance of precipitation is 60%.
Saturday
A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 89.
Saturday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 75.
Sunday
Mostly sunny, with a high near 95.
Sunday Night
Mostly clear, with a low around 77.
Monday
Sunny, with a high near 96.
Monday Night
Mostly clear, with a low around 78.
Tuesday
A 20 percent chance of showers and thunderstorms. Sunny and hot, with a high near 97.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Collinsville IL
 38.7°N 90°W (Elev. 499 ft)
Last Update:
9:26 pm CDT Jun 23, 2026
Forecast Valid:
11pm CDT Jun 23, 2026-6pm CDT Jun 30, 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