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

93°F

34°C

Humidity 58%
Wind Speed S 7 mph
Barometer 29.95 in (1013.8 mb)
Dewpoint 76°F (24°C)
Visibility 10.00 mi
Heat Index106°F (41°C)
Last update 18 Aug 5:53 pm CDT
Extended Forecast for

Swansea IL

Heat Advisory August 18, 05:59pm until August 19, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 18, 05:59pm until August 19, 08:00pm

    NOW until 8:00pm Tue

    Heat Advisory

  • Tonight

    Low: 75 °F

    Mostly Clear
    then Slight
    Chance
    T-storms

  • Tuesday

    Tuesday: A slight chance of showers and thunderstorms before 9am, then a slight chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 94. Heat index values as high as 106. Calm wind becoming northwest 5 to 7 mph in the morning. Chance of precipitation is 20%.

    High: 94 °F

    Slight Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A 40 percent chance of showers and thunderstorms, mainly before 1am. Partly cloudy, with a low around 73. North wind around 6 mph becoming calm in the evening.

    Low: 73 °F

    Chance
    T-storms

  • Wednesday

    Wednesday: A 20 percent chance of showers and thunderstorms. Partly sunny, with a high near 87. Light north wind becoming northeast 5 to 9 mph in the morning.

    High: 87 °F

    Slight Chance
    T-storms

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 66. North wind 5 to 8 mph.

    Low: 66 °F

    Partly Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 87.

    High: 87 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 67.

    Low: 67 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 88.

    High: 88 °F

    Sunny

Detailed Forecast

Tonight
A slight chance of showers and thunderstorms before 2am, then a slight chance of showers and thunderstorms after 4am. Mostly clear, with a low around 75. Southeast wind around 6 mph becoming calm after midnight. Chance of precipitation is 20%.
Tuesday
A slight chance of showers and thunderstorms before 9am, then a slight chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 94. Heat index values as high as 106. Calm wind becoming northwest 5 to 7 mph in the morning. Chance of precipitation is 20%.
Tuesday Night
A 40 percent chance of showers and thunderstorms, mainly before 1am. Partly cloudy, with a low around 73. North wind around 6 mph becoming calm in the evening.
Wednesday
A 20 percent chance of showers and thunderstorms. Partly sunny, with a high near 87. Light north wind becoming northeast 5 to 9 mph in the morning.
Wednesday Night
Partly cloudy, with a low around 66. North wind 5 to 8 mph.
Thursday
Mostly sunny, with a high near 87.
Thursday Night
Mostly clear, with a low around 67.
Friday
Sunny, with a high near 88.
Friday Night
Mostly clear, with a low around 68.
Saturday
Mostly sunny, with a high near 87.
Saturday Night
Mostly clear, with a low around 63.
Sunday
Sunny, with a high near 81.
Sunday Night
Partly cloudy, with a low around 58.
Monday
Mostly sunny, with a high near 78.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Swansea IL
 38.55°N 89.95°W (Elev. 541 ft)
Last Update:
4:16 pm CDT Aug 18, 2025
Forecast Valid:
5pm CDT Aug 18, 2025-6pm CDT Aug 25, 2025
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

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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