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

Dangerous Heat and Heavy Rainfall into the Weekend

Hot temperatures and high humidity are forecast to continue across the mid-Mississippi Valley into this weekend. Heat Advisories remain in effect. Heavy to excessive rainfall occurring at times through the weekend could bring areas of flooding to parts of the northern Rockies, upper Midwest, central Great Lakes, and southern New England. Read More >

Hazardous Weather Conditions

Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

75°F

24°C

Humidity 84%
Wind Speed S 5 mph
Barometer 29.96 in (1014.2 mb)
Dewpoint 70°F (21°C)
Visibility 10.00 mi
Last update 19 Sep 2:53 am CDT
Extended Forecast for

Belleville IL

Heat Advisory September 19, 03:52am until September 19, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory September 19, 03:52am until September 19, 08:00pm

    NOW until 8:00pm Sat

    Heat Advisory

  • Overnight

    Low: 74 °F

    Clear

  • Saturday

    Saturday: Mostly sunny and hot, with a high near 99. West wind 3 to 8 mph.

    High: 99 °F

    Hot

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 74. Light and variable wind becoming south around 5 mph in the evening.

    Low: 74 °F

    Partly Cloudy

  • Sunday

    Sunday: A 20 percent chance of showers and thunderstorms after 4pm. Mostly sunny, with a high near 94. West wind 3 to 7 mph.

    High: 94 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Sunday Night

    Sunday Night: A chance of showers and thunderstorms before 1am, then showers likely and possibly a thunderstorm between 1am and 4am, then showers likely after 4am. Mostly cloudy, with a low around 68. Northeast wind 6 to 9 mph. Chance of precipitation is 60%.

    Low: 68 °F

    Chance
    Showers then
    Showers
    Likely

  • Monday

    Monday: Showers likely and possibly a thunderstorm before 10am, then showers likely between 10am and 1pm, then showers likely and possibly a thunderstorm after 1pm. Mostly cloudy, with a high near 80. Chance of precipitation is 60%.

    High: 80 °F

    Showers
    Likely

  • Monday Night

    Monday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 61. Chance of precipitation is 30%.

    Low: 61 °F

    Chance
    Showers

  • Tuesday

    Tuesday: Partly sunny, with a high near 72.

    High: 72 °F

    Partly Sunny

Detailed Forecast

Overnight
Clear, with a low around 74. Light south wind.
Saturday
Mostly sunny and hot, with a high near 99. West wind 3 to 8 mph.
Saturday Night
Partly cloudy, with a low around 74. Light and variable wind becoming south around 5 mph in the evening.
Sunday
A 20 percent chance of showers and thunderstorms after 4pm. Mostly sunny, with a high near 94. West wind 3 to 7 mph.
Sunday Night
A chance of showers and thunderstorms before 1am, then showers likely and possibly a thunderstorm between 1am and 4am, then showers likely after 4am. Mostly cloudy, with a low around 68. Northeast wind 6 to 9 mph. Chance of precipitation is 60%.
Monday
Showers likely and possibly a thunderstorm before 10am, then showers likely between 10am and 1pm, then showers likely and possibly a thunderstorm after 1pm. Mostly cloudy, with a high near 80. Chance of precipitation is 60%.
Monday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 61. Chance of precipitation is 30%.
Tuesday
Partly sunny, with a high near 72.
Tuesday Night
Mostly cloudy, with a low around 55.
Wednesday
Mostly sunny, with a high near 75.
Wednesday Night
Partly cloudy, with a low around 56.
Thursday
Mostly sunny, with a high near 77.
Thursday Night
Mostly cloudy, with a low around 58.
Friday
Partly sunny, with a high near 79.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Belleville IL
 38.52°N 89.98°W (Elev. 509 ft)
Last Update:
1:26 am CDT Sep 19, 2026
Forecast Valid:
3am CDT Sep 19, 2026-6pm CDT Sep 25, 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