When will the Canada wildfire smoke clear? Not as soon as you'd like.

UPDATE: Jun. 8, 2023, 11:20 a.m. EDT This article was originally published Wednesday, June 7. It was updated about a day after its initial publication to reflect the facts as of Thursday, June 8.

Much of the northern U.S. is experiencing a sky darkened by a downright frightening layer of wildfire smoke that descended on Tuesday, prompting the cancellation of many outdoor events.

The source is a coast-to-coast belt of 250 wildfires across the northern border — a pattern so severe that the Canadian government is warning citizens that 2023 may prove to be the nation’s worst fire year ever.

Wildfires can be normal and healthy parts of an ecosystem, but today's fires can burn into unnatural infernos, producing unhealthy smoke that adversely impacts people's health hundreds of miles away. Different regions, at different times of year, will have a variety of influences stoking flames. Yet the continually warming atmosphere, which turns vegetation into profoundly parched fuel, is often a significant contributor in extreme fires, as are overgrown and mismanaged forests, invasive plants, and other factors.

For Americans in the densely populated northeast, including New York City — as well as parts of the midwest as of Thursday morning — it’s reasonable to ask when the smoke from this fire will finally clear up.

But those affected by the invading smoke aren’t going to like the answer.

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When will the wildfire smoke be gone?

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Technically speaking, that answer is no one knows. But if you’re in desperate need of relative certainty, then: at least not until Friday morning, according to a projection at the University of Wisconsin—Madison’s Space Science and Engineering Center. 

When this article was first published, the smoke, with its harmful particulate matter, gasses, and liquid droplets, was expected to get worse before getting better — and that's pretty much what had happened as of Thursday. The problem spread west to places like Ohio, and south to the Carolinas. All the while, the New York City area continues to suffer.

Accuweather meteorologist Tom Kines predicted to a local paper called The Staten Island Advance on Wednesday that smoke Will "still be an issue" Wednesday and Thursday, and, "probably into Friday, too." 

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Does the weather forecast say the smoke will clear soon?

Some light rain is expected on Friday, and water droplets like rain have been demonstrated to attract aerosol particles, making rain theoretically capable of "cleaning" the air. In practice, however, rain is not some reliable atmospheric janitor. 

And remember: the smoke from this crop of wildfires first drifted into the US last month. It might dissipate, only to return in a matter of weeks thanks to a different fire, and a different atmospheric pattern.

In fact, even a strong wind and a few days of dissipation won’t fully clear out the materials lingering in the environment after the initial haze has gone away. As noted by University of Montana atmospheric chemist Bob Yokelson, speaking to Discover Magazine in 2020, low concentrations of smoke can hang around and combine with the pollution already in the air. So even when it’s gone, it still may not be gone.

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How can I plan around the wildfire smoke?

All that potential lingering is important to keep in mind as you make your plans for the next few weeks. New York City’s usually clean air is some of the most hazardous in the world right now. New York City’s real-time air quality monitor site showed a staggering jump in pollution Tuesday and Wednesday. But the departure of this ominous orange miasma may not coincide with a just-as-rapid return to healthy air quality. Indeed, as of Thursday, New York City air had improved significantly, but while no longer at the "Hazardous" level, most of the five boroughs were breathing "Very Unhealthy" air.

While the air quality outside is at these levels, it’s a good idea to not just stay inside, but avoid things like candles and gas appliances that require ventilation you can’t provide. Your lungs need all the help they can get right now.