Air quality alerts posted for Chicago, New York City, Boston as Canadian wildfire smoke invades US

Air quality concerns persist for Northeast, Upper Midwest due to Canadian Wildfire smoke

A ridge of high pressure allowed smoke to filter into parts of the Northeast almost all week. While the smoke never made it's way to the surface, it did move into the mid-levels allowing for a hue across some Northeast locations.

CHICAGO – Chicago had the worst air quality overnight Wednesday into Thursday, the latest American city to feel the impact of wildfire smoke drifting south from Canada, as states across the Upper Midwest, Great Lakes and Northeast are covered in air quality alerts.

The smoke is being pulled down by the backside of a trough from more than 100 deadly wildfires that are burning in Canada, many of them not under control.

Chicago's health department warned groups that are sensitive to poor air quality to reduce their time outdoors Thursday.

Changes in the weather pattern will see some of the smoke move out of both the Midwest and Northeast by the end of Thursday.

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Chicago had an air quality index (AQI) rating of 161 on Wednesday, according to the FOX Forecast Center.

AQI ratings between 200 and 400, which are considered to be unhealthy or even hazardous.

A value between 0 and 50 on the AQI scale is considered "good," while anything over 301 reaches dangerous levels.

Timelapse video showed persistent smoke and haze over the Windy City.

Timelapse shows Canadian wildfire smoke and haze over Chicago

Timelapse shows Canadian wildfire smoke and haze over Chicago on Wednesday.

Meanwhile, air quality issues in the Northeast are being fueled by both the smoke and surface-level ozone that's being released as the region experiences its first summer-like temperatures of the season.

Air quality alerts cover both the New York City and Boston metro areas.

This graphic shows Air Quality Alerts for the Northeast for Thursday, June 5, 2025.

(FOX Weather)

The wildfire smoke brought more blood-red sunrises to the area, somewhat reminiscent, but not to the extent of the eerie orange-red skies that were observed during the 2023 Canadian wildfire season.

Canadian wildfire smoke creates hazy, orange sunrise over Boston

Canadian wildfire smoke created a hazy, orange sunrise over Boston Wednesday morning.

Marquette, Michigan, had an AQI rating of 817 on Tuesday afternoon, while the town of Hancock, Michigan, peaked over 800 late Tuesday morning. 

Smoke was still an issue across Michigan's Upper Peninsula Wednesday, with the web camera from the Mackinac Bridge showing much of the bridge obscured. 

The smoke will begin to clear across the country on Thursday evening and continue to lessen heading into the weekend.