Chicago summer forecast: less extreme heat, not as much wildfire smoke as last year but muggier

Chicagoans are likely to face the usual hot, muggy and wet summer this year but with less extreme heat and nowhere near as much smoke from wildfires as last year.

That’s what experts predict after last summer saw Chicago’s air quality rated as the dirtiest in the world at times among big cities due to drifting smoke from Canadian wildfires.

“Because we have had such a wet spring across much of the region, I wouldn’t expect a summer with a large number of extremely hot days,” says Trent Ford, the Illinois state climatologist. “But the abundant moisture in the ground can make for some very humid conditions this summer, which can exacerbate heat stress. So the outlook right now is for a warm — likely muggy — and stormy summer across the Midwest.”

Ford and others predict smoke from fires across North America in the coming months to pollute the air, though not as badly as last year, when the thick haze led to potentially harmful air quality, especially for people with health problems.

This year's fire season in Canada is predicted to be “above normal” but not even close to as bad as last year's with its unprecedented level of wildfires, according to John Abatzoglou, a University of California, Merced, professor in the school of engineering who's an expert on climate and weather.

“ 'Above normal' doesn’t mean we’re looking at a repeat” of last year, Abatzoglou says, with western Canada now largely experiencing “holdover” fires reignited from last year’s massive blazes.

Wildfires in the western United States last year were relatively tame, according to Abatzoglou, who says they could be worse this year.

Big summer fires out West have become more common over the past half century. They affect Chicago and the rest of the Midwest. But that's only part of what causes pollution and breathing problems. Exhaust from cars, trucks, trains and other vehicles that run on fossil fuels combined with emissions from factories and other sources mix with the smoke to create dangerous conditions for breathing in the summer.

The emissions cook in the atmosphere, creating ozone pollution during hot, sunny periods and spewing tiny, potentially harmful particles into the air.

“The U.S. has been cutting its human-caused pollution for decades,” says Tracey Holloway, a University of Wisconsin-Madison professor who leads an air-quality research team. “We’re seeing warmer springs and warmer summers that may be leading to high ozone levels that undo some of the pollution reductions we’ve seen."

Along with the rise in fires, the mix of pollutants can lead to unclean air that's been prompting government alerts that have become a staple of Chicago summers.

Health officials urge anyone with respiratory illnesses to monitor air-quality reports and take precautions such as avoiding going outdoors during the worst of it.

In Chicago, public health officials have been meeting weekly with a team of Northwestern University researchers and community representatives to try to better understand who is most vulnerable to illness and how many people die from summer heat, according to Raed Mansour, director of environmental innovation for the Chicago Department of Public Health.

Insurers and other financial services companies also are “focusing more and more on this type of risk” from heat and climate change to assess how it affects businesses and human health, says Dale Hall, managing director of research for the Society of Actuaries.

In the Chicago area, average annual temperatures have risen from less than 49 degrees in the mid-20th century to almost 51 degrees, Hall says.