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

Heat Persists in the South Central U.S. and Southwest; Heavy rains in the Desert Southwest and Central Plains

Sweltering heat remains across the South-Central Plains, Lower/Middle Mississippi Valley, and the Southwest this week with limited nighttime relief. Thunderstorms will bring heavy rainfall leading to localized flash flooding in portions of the Desert Southwest and central Plains. Isolated strong to severe thunderstorms are possible across portions of the central Plains into the Northeast. Read More >

Hazardous Weather Conditions

Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

76°F

24°C

Humidity 72%
Wind Speed Calm
Barometer 30.06 in (1017.3 mb)
Dewpoint 66°F (19°C)
Visibility 10.00 mi
Heat Index78°F (26°C)
Last update 9 Sep 12:53 am CDT
Extended Forecast for

Caseyville IL

  • Overnight

    Overnight: Clear, with a low around 75. South wind around 7 mph.

    Low: 75 °F

    Clear

  • Wednesday

    Wednesday: A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Increasing clouds and hot, with a high near 97. Heat index values as high as 105. South wind 7 to 9 mph becoming northwest in the morning. Chance of precipitation is 30%.

    High: 97 °F

    Slight Chance
    Showers then
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: Showers and thunderstorms likely, then showers and possibly a thunderstorm after 1am. Low around 73. Northwest wind 5 to 7 mph becoming calm in the evening. Chance of precipitation is 90%.

    Low: 73 °F

    T-storms
    Likely then
    T-storms

  • Thursday

    Thursday: Showers and possibly a thunderstorm before 1pm, then a chance of showers and thunderstorms, mainly between 1pm and 3pm. High near 80. Calm wind becoming west around 6 mph in the morning. Chance of precipitation is 90%.

    High: 80 °F

    Showers then
    Showers
    Likely

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 66. North wind around 5 mph becoming calm in the evening.

    Low: 66 °F

    Mostly Cloudy

  • Friday

    Friday: A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 86.

    High: 86 °F

    Mostly Sunny
    then Slight
    Chance
    Showers

  • Friday Night

    Friday Night: Mostly clear, with a low around 68.

    Low: 68 °F

    Mostly Clear

  • Saturday

    Saturday: A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 92.

    High: 92 °F

    Slight Chance
    T-storms

  • Saturday Night

    Saturday Night: A 30 percent chance of showers and thunderstorms, mainly before 1am. Partly cloudy, with a low around 70.

    Low: 70 °F

    Chance
    T-storms

Detailed Forecast

Overnight
Clear, with a low around 75. South wind around 7 mph.
Wednesday
A slight chance of showers, then a chance of showers and thunderstorms after 1pm. Increasing clouds and hot, with a high near 97. Heat index values as high as 105. South wind 7 to 9 mph becoming northwest in the morning. Chance of precipitation is 30%.
Wednesday Night
Showers and thunderstorms likely, then showers and possibly a thunderstorm after 1am. Low around 73. Northwest wind 5 to 7 mph becoming calm in the evening. Chance of precipitation is 90%.
Thursday
Showers and possibly a thunderstorm before 1pm, then a chance of showers and thunderstorms, mainly between 1pm and 3pm. High near 80. Calm wind becoming west around 6 mph in the morning. Chance of precipitation is 90%.
Thursday Night
Mostly cloudy, with a low around 66. North wind around 5 mph becoming calm in the evening.
Friday
A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 86.
Friday Night
Mostly clear, with a low around 68.
Saturday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 92.
Saturday Night
A 30 percent chance of showers and thunderstorms, mainly before 1am. Partly cloudy, with a low around 70.
Sunday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 90.
Sunday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 69.
Monday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 91.
Monday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 70.
Tuesday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 88.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Caseyville IL
 38.64°N 90.03°W (Elev. 446 ft)
Last Update:
11:56 pm CDT Sep 8, 2026
Forecast Valid:
1am CDT Sep 9, 2026-6pm CDT Sep 15, 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