Tracking the Smoke From the Canadian Fires

Smoke and haze filled the skies across the Northeast on Tuesday, as wildfires burning hundreds of miles away in Canada made the air unhealthy in New York City, Boston and elsewhere. More than 150 fires were active in Quebec alone, according to the Canadian Interagency Forest Fire Centre.

The forecast computer model in the map above shows where the thickest smoke is likely near the surface over the next several hours.

Many of the fires burning in Quebec started days ago, if not weeks. But a storm system swirling off the coast of Nova Scotia forced the smoke from these fires south into the United States, and then east — toward some of the most densely populated areas in the country.

The weather pattern pushing smoke to the Northeast is expected to persist for the next several days, with haze likely to continue across the region.

The level of particulate matter in the air from smoke on Tuesday evening was considered unhealthy from North Dakota and Missouri to Pennsylvania and Virginia, according to AirNow, a source for air quality data. In Ottawa and Brooklyn, the air quality was considered hazardous.

Many of the fires in Quebec were ignited by lightning earlier this month, but above-normal temperatures and dry conditions have helped fuel outbreaks across the country since last month.

So far this year, 600 square miles have burned throughout Quebec, according to NASA. In a typical year, barely a square mile would have burned, according to the province’s fire prevention agency.

Fire season in Quebec and Canada usually starts in May, slightly before the typical start of fire activity in the United States. So far there have been few major U.S. fire outbreaks. But as blazes in recent years have been erupting more frequently, the fire season has lasted longer and has been more destructive.