Naperville, Illinois Weather:
Active Weather Warnings
Sunday, September 20, 2026
Rainy Weather
Day 70°
Night 61°
Precipitation 80 %
Wind 10 mph
UV Index (0 - 11+) 1
Weather Forecast History
Last Year's Weather on This Day (September 20, 2025)
Stormy Weather

Day

77°

Night

64°

Wind

5 mph

Precipitation

88 %

Weather Alerts and Warnings for

Severe Future Possible

Flood Watch

Flood Watch issued September 19 at 10:34AM CDT until September 20 at 7:00AM CDT by NWS Chicago IL
Sep 19, 10:34 AM Sep 20, 7:00 AM
WHAT: Flash flooding caused by excessive rainfall continues to be
possible.

WHERE: Portions of Illinois, including the following areas, Boone,
Central Cook, De Kalb, DuPage, Kane, Kendall, Lake IL, Lee,
Northern Cook, Northern Will, Ogle and Southern Cook and northwest
Indiana, including the following areas, Lake IN and Porter.

WHEN: Through early Sunday morning.

IMPACTS: Creeks and streams may rise out of their banks. Flooding
may occur in poor drainage and urban areas. Roads and streets may
be flooded.

ADDITIONAL DETAILS:
- An additional round of showers and thunderstorms, some with very
heavy rainfall, are expected this evening and overnight which may
result in areas of flash flooding, particularly over urban or
areas of poor drainage.
- http://www.weather.gov/safety/flood
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A Flood Watch for flash flooding means rapid-onset flooding is possible, but not yet certain, based upon the latest forecasts. Flash flooding is a dangerous situation. Persons with interests along area rivers, creeks, and other waterways should monitor the latest forecasts and be prepared to take action should flooding develop.
Updated: Sep 19, 11:12 AM Source: NWS Alert