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

67°F

19°C

Humidity 45%
Wind Speed S 10 G 17 mph
Barometer 30.12 in (1019.6 mb)
Dewpoint 45°F (7°C)
Visibility 10.00 mi
Last update 21 Apr 9:53 am CDT
Extended Forecast for

Collinsville IL

  • Today

    Today: Sunny, with a high near 81. Southwest wind 11 to 16 mph, with gusts as high as 24 mph.

    High: 81 °F

    Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 58. Southwest wind 7 to 11 mph.

    Low: 58 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny, with a high near 79. Southwest wind 6 to 9 mph.

    High: 79 °F

    Sunny

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 58. South wind around 7 mph.

    Low: 58 °F

    Mostly Clear

  • Thursday

    Thursday: Mostly sunny, with a high near 83. South wind 7 to 12 mph increasing to 13 to 18 mph in the afternoon. Winds could gust as high as 28 mph.

    High: 83 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 63. Chance of precipitation is 60%.

    Low: 63 °F

    Mostly Cloudy
    then Showers
    Likely

  • Friday

    Friday: Showers and possibly a thunderstorm. High near 77. Chance of precipitation is 80%.

    High: 77 °F

    Showers

  • Friday Night

    Friday Night: A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 56.

    Low: 56 °F

    Chance
    T-storms

  • Saturday

    Saturday: A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 75.

    High: 75 °F

    Mostly Sunny
    then Slight
    Chance
    Showers

Detailed Forecast

Today
Sunny, with a high near 81. Southwest wind 11 to 16 mph, with gusts as high as 24 mph.
Tonight
Mostly clear, with a low around 58. Southwest wind 7 to 11 mph.
Wednesday
Sunny, with a high near 79. Southwest wind 6 to 9 mph.
Wednesday Night
Mostly clear, with a low around 58. South wind around 7 mph.
Thursday
Mostly sunny, with a high near 83. South wind 7 to 12 mph increasing to 13 to 18 mph in the afternoon. Winds could gust as high as 28 mph.
Thursday Night
Showers likely and possibly a thunderstorm after 1am. Mostly cloudy, with a low around 63. Chance of precipitation is 60%.
Friday
Showers and possibly a thunderstorm. High near 77. Chance of precipitation is 80%.
Friday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 56.
Saturday
A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 75.
Saturday Night
A slight chance of showers, with thunderstorms also possible after 1am. Partly cloudy, with a low around 53. Chance of precipitation is 20%.
Sunday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 74.
Sunday Night
Showers and thunderstorms likely. Mostly cloudy, with a low around 59. Chance of precipitation is 60%.
Monday
Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 75. Chance of precipitation is 60%.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Collinsville IL
 38.68°N 90.03°W (Elev. 427 ft)
Last Update:
8:41 am CDT Apr 21, 2026
Forecast Valid:
10am CDT Apr 21, 2026-6pm CDT Apr 27, 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