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Illinois Air Quality

St. Louis (Metro-east) is the worst air in Illinois right now at an index of 61, which is Moderate, from fine particles (PM2.5). AirNow carries 14 reporting areas in the state. No air quality alert is in force. Wildfire smoke has been drawn over 127 of the state’s towns today.

Reporting areas: 14
Worst index now: 61
Alerts in force: 0
Towns under smoke: 127

Fine particles on the map

Forecast fine particulate matter from NOAA’s National Air Quality Forecast Capability over Illinois. Open it for the live map, where it pans and zooms.

Open the live map with the particulate forecast

Map layer from NOAA National Air Quality Forecast Capability. Boundaries from the Iowa Environmental Mesonet.

Alerts in force

An Air Quality Alert is issued by the National Weather Service on behalf of a state or local agency when pollution is expected to reach a level that harms health. An Air Stagnation Advisory means the air will not move enough to clear what is already in it.

None are in force in Illinois right now. All Illinois warnings.

By city, now and the days ahead14

Every AirNow reporting area in Illinois: what its monitors measured this hour, and what the state or local agency that forecasts for it expects today and tomorrow. Each area links to the nearest town’s page.

Reporting area	Now	Category now	Today	Tomorrow	Pollutant
St. Louis (Metro-east)	61	Moderate	Moderate	Good	PM2.5
Decatur	44	Good	Moderate	Good	Ozone
Springfield	41	Good	Moderate	Good	Ozone
Champaign	40	Good	Moderate	Good	Ozone
Bloomington and Normal	37	Good	Moderate	Good	Ozone
Peoria	33	Good	Moderate	Good	Ozone
Lake County	24	Good	Good	Good	Ozone
North and West Suburbs (Chicago)	24	Good	Good	Good	Ozone
Chicago	20	Good	Good	Good	Ozone
Rockford	20	Good	Good	Good	Ozone
Aurora and Elgin	19	Good	Good	Good	Ozone
South and West Suburbs (Chicago)	19	Good	Good	Good	PM2.5
Joliet and Will County	18	Good	Good	Good	PM2.5
Rock Island-Moline	18	Good	Good	Good	Ozone

Smoke

Where NOAA’s Hazard Mapping System analysts have drawn wildfire smoke over Illinois in today’s satellite imagery. Smoke drawn overhead is not always smoke at ground level; each town’s page carries the near-surface forecast.

Medium Belleville, Upper Alton, Granite City, O'Fallon, East Saint Louis, Alton, Carbondale, Edwardsville, Collinsville, Charleston, Mattoon, Marion, Godfrey, Fairview Heights, Mount Vernon, Cahokia and 40 more
Light Peoria, Springfield, North Peoria, Champaign, Bloomington, Decatur, Normal, Urbana, Quincy, Pekin, Danville, Galesburg, Chicago Heights, Lansing, Kankakee, New Lenox and 55 more

Smoke on the radar over Illinois

What this means

The index runs from 0 to 500. Good is 0 to 50, Moderate to 100, Unhealthy for Sensitive Groups to 150, Unhealthy to 200, Very Unhealthy to 300, and Hazardous above that. The figure reported for a place is the highest index among the pollutants measured there, and the pollutant that produced it is named beside it.

What these numbers are. An index beside a monitor’s name is a measurement, published hourly by AirNow and preliminary until the operating agency certifies it. A category for today or tomorrow is a state or local agency forecaster’s own forecast for a reporting area. An hourly index is NOAA’s air quality model on a five-kilometer grid, not a reading from any instrument. Where a town has no monitor within reach, only the model figures appear, and the page says so.

Towns

Air quality for any town in Illinois: what is measured nearby, the category forecast for today and tomorrow, and NOAA’s model hour by hour. Largest first.

564 smaller towns

Smaller places have pages too; search for one on the air quality landing page.

Sources

Observations and daily forecasts from AirNow, the US Environmental Protection Agency’s program with NOAA, the National Park Service, NASA, tribal, state and local agencies. Hourly forecasts from NOAA’s National Air Quality Forecast Capability. Smoke analysis from NOAA’s Hazard Mapping System. Alerts from the National Weather Service. Index categories and breakpoints are EPA’s, as revised in 2024.