Chicago’s air quality is expected to be poor through Thursday night as smoke from Canadian wildfires lingers in the metro area, continuing a state air quality alert that has been in effect for most of the last week.
The Illinois Environmental Protection Agency extended its Air Pollution Action Day alert from Wednesday afternoon to midnight Friday. The Chicago area has been under the alert for poor air quality since last Thursday, when the city briefly had the worst air pollution of any city in the world.
Meanwhile, the temperatures and humidity levels in the city are also expected to increase each day until Saturday, according to the National Weather Service.
Air Pollution Action Day alerts are issued when air quality is such that widespread ozone and/or particulate levels are expected to be at or above levels that are unhealthy for sensitive groups.
“If necessary, we will extend the Air Pollution Action Day until Friday, if conditions warrant,” Kim Biggs, spokesperson for the Illinois EPA, told the Sun-Times.
While particulates in the air from Canadian wildfire smoke have started to dip, the current levels of ozone have prompted the agency to extend the alert, she said.
On Wednesday, the city recorded 93 on the Air Quality Index, which is considered a moderate level with some risk for those unusually sensitive to air pollution.
Keep an eye out for patchy dense fog this morning for the start of the AM commute. Hazy skies from wildfire smoke also continue today but improvement is possible overnight into Thursday. Increasing heat and humidity is then expected through the end of the week. #ILwx #Nwx pic.twitter.com/1UBspFH12T
— NWS Chicago (@NWSChicago) August 6, 2025
Chicago is expecting seasonably warm weather this week, but it should be less intense than last week.
The weather agency said Chicago reached the mid-80s, while Thursday is expected to reach 90 degrees. This could increase to the low 90s on Saturday, which could be the warmest day of the week.
The heat index — which is the apparent temperature or what it feels like — is also said reach the range of mid-90s to 100 on Saturday.
“It’ll be more humid, but it won’t be of the magnitude of heat and humidity that we saw like a week or two ago. It won’t be quite as bad as that,” said Mark Ratzer, the lead meteorologist at the National Weather Service.
While the weather remains seasonably warm, it is considered normal for this time of the year. The agency said the normal high for this time of the year is about 84 degrees, making this week slightly hotter than normal.
General caution to remain indoors during the high temperatures along with the need for hydration is advised for sensitive groups and the elderly.
Temperatures are expected to get slightly cooler next week as some children return to school.
Sunday night could be slightly cooler with more cloud cover and increasing rain chances, Ratzer said.