Tomorrow | Weather | Naperville, Illinois

Active Weather Warnings
Tuesday, July 21, 2026
Sunny with a Chance of Thunderstorms
Day 84°
Night 61°
Precipitation 55 %
Wind 13 mph
UV Index (0 - 11+) 6
Weather Forecast History
Last Year's Weather on This Day (July 21, 2025)
Cloudy Night

Day

86°

Night

68°

Wind

6 mph

Precipitation

12 %

Weather Alerts and Warnings for

Air Quality Alert

Air Quality Alert issued July 19 at 12:50PM CDT by NWS Chicago IL
Jul 19, 12:50 PM Jul 21, 12:00 AM
The Illinois Environmental Protection Agency has issued an Areawide
Air Pollution Action Day for Monday July 20th for portions of
Illinois. This is in addition to the ongoing Areawide Air Pollution
Action Day in effect today July 19th for the same areas.

An Areawide Air Pollution Action Day is declared when weather
conditions are such that widespread ozone and or particulate levels
are forecast to be at or above the Unhealthy for Sensitive Groups
(USG) category in all or nearly all Illinois AQI forecast sectors.

Areas both inside and outside of the Action Day coverage area are
likely to see smoke/particulates to a varying degree and duration
today and Monday with smoke likely decreasing from southwest to
northeast through the day Monday. Those with air quality concerns or
anyone in Illinois with outdoor plans is encouraged to check current
NowCast readings or sign up for EnviroFlash alerts on AirNow. gov.
Before going outside, checking the NowCast AQI will help identify
periods of both poor and cleaner air quality regardless of the level
of the daily 24-hour AQI forecast.

AQI Category Guidance Unhealthy for Sensitive Groups (USG) - Members
of sensitive groups may experience health effects. The general
public is less likely to be affected. Sensitive groups: Make outdoor
activities shorter and less intense. Its OK to be active outdoors,
but take more breaks. Watch for symptoms such as coughing or
shortness of breath. People with asthma: Follow your asthma action
plan and keep quick relief medicine handy. People with heart disease:
Symptoms such as palpitations, shortness of breath, or unusual
fatigue may indicate a serious problem. If you have any of these,
contact your health care provider. Unhealthy - Sensitive groups:
Avoid long or intense outdoor activities. Consider rescheduling or
moving activities indoors. Everyone else: Reduce long or intense
activities. Take more breaks during outdoor activities.


Media Contact... Illinois EPA
Updated: Jul 20, 6:18 PM Source: NWS Alert