But Environment Canada forecast little relief from the weather, saying the fire areas would get isolated showers and possibly thunderstorms on Monday afternoon and into Tuesday.

The next few days were expected to offer cooler, sunny weather, but little rain.

"We would need at least two or three days of rain to get a grip on the fires, whereas one day offers only a little help," said Eric Santerre, spokesman for the Quebec Forest Service.

"Such a small amount of rain will make it very difficult. This is one of the worst years in the last decade."

The largest of the wildfires, burning in the remote northern James Bay region, has consumed more than 600 square kilometres (148,000 acres) of forest.

Already this year, 360 fires have consumed over 2,000 square kilometres (500,000 acres) of forest in Quebec, compared with a same-date average of 469 fires and 268 square kilometres (66,000 acres) over the past five years.

After blanketing southern Quebec and parts of Ontario and the northern United States with smoke and an eerie yellow haze on Sunday, the smoke was now moving eastward into New Brunswick, Nova Scotia and Maine.

Environment Canada, which on Monday issued smog advisories for many Canadian cities including Toronto, recommended that the elderly and people with breathing problems should be cautious.

HAZE OVER WASHINGTON

U.S. National Weather Service meteorologist Andy Woodcock told Reuters that the combination of stagnant summer air and cooler temperatures have smoke and haze trapped for a second day over the U.S. capital.

"We've got this trap over us and there's not really any strong wind," the Baltimore-Washington area meteorologist said. "We don't even have any good heating to burn the smoke."

A cold front expected on Wednesday should start to push the haze out of the area, he said.

The idea that fires some 1,300 km (800 miles) away have affected the air quality of Washington is quite unusual, he added.

"It's somewhat of an anomaly. You have to have the right kind of conditions. Because the winds were straight out of the north from central Canada, it funneled it down here," he said.

The Metropolitan Washington Council of Governments, which issues air quality warnings tied to ozone levels for the capital region, said Monday was a "code orange" day, or unhealthy for sensitive groups like the elderly or people with respiratory problems, a spokeswoman said.

The smoke and haze were not factored into Monday's warning, but would pose similar health hazards to groups affected by code orange day, the nonprofit government group said.

The council has a scale that rates air quality from green (good), through yellow, orange and red to a very unhealthy purple.

(Additional reporting by Niala Boodhoo in Washington).