NEW YORK (AP) — Millions of people in the Great Lakes, Northeast and Mid-Atlantic states muddled through another day of unhealthy air from uncontrolled wildfires on Friday, as smoke enveloped the nation’s capital in a gloomy, eerie haze.

Air quality warnings were expected to remain in effect through Saturday across a wide swath of the U.S., but there’s potential for temporary relief with rains and storms forecast over a chunk of the affected region over the weekend.

The smoky conditions won’t be gone anytime soon, though, as fires burn unchecked across a remote region of Canada, cautioned Bob Oravec, a lead forecaster at the National Weather Service based in Maryland. Wildfires in a wilderness area in Minnesota are also contributing to the smoke.

“The source of the smoke is going to continue on for certainly a week, probably,” he said. “So in some form, there’s going to be smoke that gets transported from the fires downstream, and it’s just going to depend upon which way the wind’s blowing as to where the smoke is going to affect the most.”

On Friday, communities in Minnesota, Michigan and Illinois closest to the Canadian border and the Boundary Waters Canoe Area Wilderness in Minnesota again registered some of the worst air quality in the world, according to IQAir, an air quality monitoring website.

Not far behind them was Washington, D.C., where the thick smoke created eerie scenes. The Washington Monument, the Lincoln Memorial and other national landmarks could be seen enveloped in a thick, orange-hued haze in the morning.

“Wow that Canadian smoke haze is no joke,” Stewart Verdery, a former assistant secretary at the U.S. Department of Homeland Security, wrote on X as he shared a panorama of D.C. at sunrise. “Almost nothing visible – no sun, no monuments, no Reagan Airport.”

Air in and around Washington was expected to go from bad to worse as the day progressed, reaching “very unhealthy” and potentially “hazardous” levels on the air quality index, regional officials said.

People, particularly those with heart or lung disease, older adults and children, were urged to limit or avoid going outside as much as possible until air quality improved.

There was also concern in the New York City area about how the foul air might impact the World Cup final match between soccer powerhouses Spain and Argentina at MetLife Stadium in New Jersey on Sunday.

Oravec said winds will continue pushing the wildfire smoke east in the U.S., though conditions should be better on game day Sunday than on Saturday.

Just a day earlier, a thick haze tinged with orange and yellow darkened skies across several states and partly obscured Manhattan’s skyline.

Officials from New York, New Jersey, Pennsylvania and other Northeast states distributed free K95 face masks, canceled outdoor programming and opened libraries and other public buildings as cooling centers where people could get a respite from the sooty air.

As Friday progressed, air quality measures improved from “unhealthy” to “moderate” in some places in and around New York City.

A strong sun broke through a thin veil of smoke, and large chunks of clear blue sky were visible across much of the region by Friday afternoon.

Saturday brings a high chance of thunderstorms across much of the Northeast and mid-Atlantic, which will help dampen the bad air.

How long the reprieve lasts depends on what happens hundreds of miles north, as some 100 wildfires burn without end in sight, largely in the Ontario area in Canada. In the U.S., officials have closed the Boundary Waters while battling multiple fires.

Long-term exposure to smoky conditions can complicate existing health problems and lead to chronic and deadly issues, including respiratory illness, cardiovascular and neurological diseases and premature death.

The common loon, Minnesota’s state bird, is more closely related to a penguin than a duck.

Fires in the past burned more frequently in western Canada, but recent years have seen that trend migrate eastward, with large fires now burning in Ontario, Quebec and Atlantic provinces, Prof Chasmer said, leading to more noticeable smoke in densely populated cities like Toronto and New York.