In addition to storms and a looming heat wave set to settle into Chicago midweek, poor air quality and hazy skies have returned to the area, leading the Environmental Protection Agency to declare an air quality action day Tuesday for nearly all of northeastern Illinois and northwest Indiana.
According to the EPA, the alert will remain in effect until midnight.
"An quality action day is declared when weather conditions are such that widespread ozone and or particulate levels are expected to be at or above the 'Unhealthy for sensitive groups' category of the air quality index for multiple days," a message from the National Weather Service read. "Active children and adults, especially people with pulmonary or respiratory disease such as asthma, should limit prolonged outdoor activity."
As of 5:30 a.m. Tuesday, AirNow.gov, the EPA's air quality tracking website, showed Chicago at a PM2.5 — an air pollutant also known as fine particulate matter, which is causing much of the haze in the region — of 150. PM2.5 readings of between 150 and 200 are classified as "Unhealthy for sensitive groups," which ranks as level three of six.
"Wildfire smoke over parts of northeast Illinois will result in a mix of 'Moderate' to 'Unhealthy for sensitive groups' PM2.5 AQI Monday," AirNow said. "Lingering smoke Tuesday may also enhance ozone development with a mix of 'Moderate" to 'Unhealthy for sensitive groups' ozone expected for Tuesday and a continued possibility of PM2.5 reaching near or at 'Unhealthy for sensitive groups' levels due to the smoke."
Haze and smoke from Canadian wildfires still burning have resulted in a handful of air quality alerts in the Chicago area throughout the summer. For one day last month, Chicago held a spot at the top of the World Air Quality Index, which ranks cities across the globe from worst air quality to best.
According to NBC 5 Meteorologist Pete Sack, the 'unhealthy' levels of wildfire smoke could persist as winds continue to shift.
Local
"The frequency is going to depend a lot on, of course, the wildfires and how bad they're burning," Sack said. "The other factor is the upper level winds."
Heat, humidity building
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Air quality concerns will coincide with the arrival of hot and humid conditions this week, as a "hot and humid airmass" is on the way, NBC 5 Meteorologist Alicia Roman says.
High temperatures beginning Tuesday will likely soar into the mid 80s to low 90s, and that pattern will continue through the remainder of the work week, with highs approaching 95 degrees by Wednesday and Thursday.
Additionally, heat indices at or near 100 could make things feel even more muggy and warm.
Strong to severe storm chance
Wednesday morning and afternoon, the Chicago area could also potentially see a threat for severe weather, with the Storm Prediction Center currently putting the region at a “slight” risk of severe storms, which ranks as level two of five.
The main threats will likely be gusty winds, but large hail cannot be ruled out, according to officials.
Highs will likely remain above 90 degrees on Friday, but there is a chance of storms that could help to provide at least a bit of relief from the heat.
That chance of thunderstorms exists again on Saturday, and high temperatures and humidity are expected to begin to drop by Sunday.
Cooling centers
"The Chicago Office of Emergency Management and Communications (OEMC) encourages residents to be prepared for temperatures reaching dangerous levels this week as temperatures are forecasted to go into the 90s," a release from the city said in a release.
Here's a list of the city's six cooling centers, which are open from 9 a.m. to 5 p.m. all week:
- Englewood Center – 1140 W. 79th Street
- Garfield Center – 10 S. Kedzie Ave. (24 Hours)
- King Center – 4314 S. Cottage Grove
- North Area Center – 845 W. Wilson Ave.
- South Chicago Center – 8650 S. Commercial Ave.
- Trina Davila Center – 4312 W. North Ave.
"During hours of operation, residents can also find relief in one of the City’s Chicago Public Library locations and Chicago Park District fieldhouses as well as splash pads located throughout the city," the release added.
According to the OMEC, the NWS will issue an "extreme heat warning" if the heat index is expected to exceed 105-110 degrees for at least two consecutive days.
