Today | Weather | Monday, July 20, 2026
Active Weather Warnings

Weather in Naperville, Illinois

12:30 AM
Now
Cloudy Night
66° F
Feels Like 64°
Precipitation 0 %
Wind 5 mph
Humidity 78 %
Today
Sunny with a Chance of Thunderstorms
Day 86°
Night 72°
Precipitation 55 %
Wind 9 mph
UV Index (0 - 11+) 10

Warning: High UV Index Today: 10

High risk of harm from unprotected sun exposure. Take precautions: wear a hat, sunglasses, and apply sunscreen regularly if you’ll be outdoors for extended periods.

Naperville Weather Forecast Updated

14 minutes ago
Last updated on
Weather Forecast History
Last Year's Weather on This Day (July 20, 2025)
Cloudy Night

Day

75°

Night

66°

Wind

6 mph

Precipitation

8 %

Air Quality in Naperville

NOW
74 AQI
Moderate air quality Dominant pollutant: PM2.5

Pollutant Concentrations:

PM2.5 23.17 µg/m³
PM10 23.52 µg/m³
O3 0.037 ppm
NO2 2.4 ppb
SO2 0.4 ppb
CO 0.67 ppm
NH3 0.71 µg/m³
NO 0 µg/m³
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide
NH3 – Ammonia
NO – Nitric oxide

Health Recommendations:

Air quality is acceptable; however, for some pollutants, there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.

Show raw pollutant concentrations (µg/m³)
PM2.523.17 µg/m³
PM1023.52 µg/m³
O371.67 µg/m³
NO24.54 µg/m³
SO21.17 µg/m³
CO768.35 µg/m³
NH30.71 µg/m³
NO0 µg/m³

Weather Alerts and Warnings for Naperville

Air Quality Alert

Air Quality Alert issued July 18 at 12:31PM CDT by NWS Chicago IL
Jul 18, 12:31 PM Jul 20, 12:00 AM
The Illinois Environmental Protection Agency has issued an Areawide
Air Pollution Action Day for Sunday July 19th for portions of
Illinois. This is in addition to the ongoing Chicago Area Air
Pollution Action Day in effect today.

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 may
experience smoke/PM2.5 to a varying degree and duration both later
today and Sunday. 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 forecasted AQI.

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 19, 10:43 PM Source: NWS Alert