Smoke from Canada's wildfires darkens Europe's skies

A plume of smoke stretches from North America across more than 2,000 miles of the Atlantic Ocean in the latest international impact from Canada's large and persistent wildfires. (NASA Earth Observatory)

Weather forecasts in Portugal are calling for skies "obscured by smoke particles" on Tuesday as Canada's persistent wildfires begin to affect Europe.

The plume of smoke and soot stretches for thousands of miles from the province of Quebec across the Atlantic Ocean, according to satellite images NASA released on Monday.

The enormous band of smoke began reaching the Azores islands on Sunday and reached western Europe on Monday, according to the Portuguese Institute for Sea and Atmosphere, or IPMA. The smoke is also affecting Spain, France and other countries to the north.

Smoke isn't posing the same health risks in Europe

Unlike the low-lying smoke that triggered hazardous air quality alerts in the U.S. earlier this month, the smoke that has reached Europe seems to be hanging higher in the air, at 1,100 meters (3,609 feet) and above, according to climate agencies.

"Whilst the smoke is high up in the atmosphere, it may make for some vivid sunrises and sunsets in the next few days," the U.K.'s Met Office said, urging Brits to keep their phones handy to capture dramatic skylines.

France's skies are expected to reach a maximum concentration of ash particles on Wednesday, according to French broadcaster La Chaîne Météo.

A NASA satellite image shows smoke from Canada's wildfires approaching southwestern Europe on Monday. The smoke is expected to remain at higher altitudes, reducing the threat to people on the ground. (NASA Earth Observatory)

Canadians are still reeling from an intense fire season

The air may be unaffected in Europe, but people closer to the fires in Quebec and other provinces are being forced to cope with smoke. As of Tuesday morning, more than 140 communities were under air quality alerts, according to federal agency Environment Canada.

For now, there's no end in sight to the fires: Canada currently has nearly 500 wildfires burning, and more than half of them (258) are out of control, according to the Canadian Interagency Forest Fire Centre. That's up from around 450 fires that were burning in mid-June.

"Already, the amount of land that's burned in Quebec this year is 10 times greater than what's been typical over the last few decades," as NPR's Nate Rott reported on Monday.

The smoke has also posed a recurring risk to people in the far northeastern U.S., depending on wind and other conditions. The Maine Department of Environmental Protection issued an air quality alert for Sunday, but it currently has no alerts in effect.

"With smoke there are so many variables at play that we don't normally issue a forecast beyond the next day," the agency says.