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

Chicago / West Chicago, Dupage Airport (KDPA)

Lat: 41.9°NLon: 88.25°WElev: 758ft.

Thunderstorm in Vicinity Rain Fog/Mist

68°F

20°C

Humidity 96%
Wind Speed NE 12 mph
Barometer 29.89 in (1012.1 mb)
Dewpoint 67°F (19°C)
Visibility 6.00 mi
Last update 20 Sep 4:52 am CDT
Extended Forecast for

Saint Charles IL

Flood Watch September 20, 05:33am until September 20, 01:00pm
Flood Advisory until September 20, 08:00am
Click here for hazard details and duration
Flood Watch
Flood Advisory
  •  
    Flood Watch September 20, 05:33am until September 20, 01:00pm
    Flood Advisory until September 20, 08:00am

    NOW: Multiple hazards in effect

    Click HERE for Details

  • Overnight

    Low: 66 °F

    Heavy Rain
    and Patchy
    Fog

  • Sunday

    Sunday: Showers and possibly a thunderstorm before 1pm, then a chance of showers and thunderstorms between 1pm and 4pm, then a chance of showers after 4pm. Some of the storms could produce heavy rainfall. Patchy fog before 10am. High near 68. Northeast wind 10 to 15 mph, with gusts as high as 30 mph. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.

    High: 68 °F

    Heavy Rain
    and Patchy
    Fog then
    Showers
    Likely

  • Sunday Night

    Sunday Night: A slight chance of showers before 7pm, then a chance of showers after midnight. Cloudy, with a low around 57. East northeast wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 30%.

    Low: 57 °F

    Chance
    Showers

  • Monday

    Monday: A 30 percent chance of showers, mainly before 9am. Mostly cloudy, with a high near 64. East northeast wind around 15 mph, with gusts as high as 25 mph.

    High: 64 °F

    Chance
    Showers

  • Monday Night

    Monday Night: A 30 percent chance of showers, mainly after 1am. Mostly cloudy, with a low around 53. Northeast wind 10 to 15 mph, with gusts as high as 20 mph.

    Low: 53 °F

    Chance
    Showers

  • Tuesday

    Tuesday: A 20 percent chance of showers before 1pm. Mostly cloudy, with a high near 62.

    High: 62 °F

    Slight Chance
    Showers

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 51.

    Low: 51 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Partly sunny, with a high near 64.

    High: 64 °F

    Partly Sunny

Detailed Forecast

Overnight
Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Patchy fog. Low around 66. Northeast wind around 5 mph. Chance of precipitation is 100%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Sunday
Showers and possibly a thunderstorm before 1pm, then a chance of showers and thunderstorms between 1pm and 4pm, then a chance of showers after 4pm. Some of the storms could produce heavy rainfall. Patchy fog before 10am. High near 68. Northeast wind 10 to 15 mph, with gusts as high as 30 mph. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.
Sunday Night
A slight chance of showers before 7pm, then a chance of showers after midnight. Cloudy, with a low around 57. East northeast wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 30%.
Monday
A 30 percent chance of showers, mainly before 9am. Mostly cloudy, with a high near 64. East northeast wind around 15 mph, with gusts as high as 25 mph.
Monday Night
A 30 percent chance of showers, mainly after 1am. Mostly cloudy, with a low around 53. Northeast wind 10 to 15 mph, with gusts as high as 20 mph.
Tuesday
A 20 percent chance of showers before 1pm. Mostly cloudy, with a high near 62.
Tuesday Night
Partly cloudy, with a low around 51.
Wednesday
Partly sunny, with a high near 64.
Wednesday Night
Partly cloudy, with a low around 50.
Thursday
Mostly sunny, with a high near 66.
Thursday Night
Mostly cloudy, with a low around 51.
Friday
Mostly sunny, with a high near 68.
Friday Night
Partly cloudy, with a low around 50.
Saturday
Mostly sunny, with a high near 71.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Saint Charles IL
 41.92°N 88.29°W
Last Update:
3:36 am CDT Sep 20, 2026
Forecast Valid:
5am CDT Sep 20, 2026-6pm CDT Sep 26, 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