Canadian wildfires will send worsening smoky air across the country and neighbouring United States in coming days after recent heavy rains failed to fall in areas of Quebec where the fires are most active, officials said on Wednesday.

Drifting smoke from the wildfires has lowered curtains of haze on broad swaths of Canada and the United States, pushing into southern Illinois, Indiana and Ohio, and moving into parts of West Virginia.

Canadian officials say it is the nation's worst wildfire season ever and they expect air quality to remain a concern through the summer, as long as the fires continue.

It started early on drier-than-usual ground and accelerated very quickly, exhausting firefighting resources across the country, fire and environmental officials said.

Environment and Climate Change Canada Meteorologist Steven Flisfeder said smoke will migrate across Quebec and Ontario over the next few days, and that air quality will deteriorate as a result.

“As long as the fires are burning and the smoke is in the atmosphere it is going to be a concern not just for Canadians but Americans as well,” Flisfeder said.

Flisfeder said the smoky, hazy skies will persist unless rainfall provides sufficient help to firefighters in controlling the blazes. “It's important to note that the highest amounts of rain were not received in those areas where most active forest fires are,” Flisfeder said.

The Detroit area woke up Wednesday to some of the worst air quality in the United States as smoke from Canada's wildfires settled over most of the Great Lakes region and unhealthy haze spread southward, as far as Missouri and Kentucky.

Meanwhile, NASA is reporting that smoke from wildfires in northern Quebec has reached Europe. The American space agency said satellite imagery from Monday showed smoke extending across the North Atlantic Ocean to the Iberian Peninsula, France and other parts of western Europe.

There are 490 fires burning nationally, with 255 of them considered to be out of control. Quebec's forest fire prevention agency is reporting 110 active fires.

Canada already surpassed the record for area burned. The Canadian Interagency Forest Fire Centre reported this week that 76,129 square kilometers (29,393 square miles) of forest and other land has burned across Canada since January 1. That exceeds the previous record set in 1989 of 75,596 square kilometers (29,187 square miles), according to the National Forestry Database.

"This season has been unprecedented,” Flisfeder said.

Almost 1,200 vulnerable people from Cree communities are among the evacuees who have fled northern Quebec because of wildfires and smoke. Dr. François Prévost of the Cree health board said the evacuation process has gone relatively well, but he adds that the situation poses particular health, logistical and cultural challenges.