A Canadian meteorologist is cited as saying Canada experiences the most pyrocumulonimbus clouds, which are generated by huge wildfires and can worsen their spread. These fire clouds, formed when hot air from a wildfire rises with moisture and smoke, can be seen up to 200 kilometers away and can reach altitudes of over a dozen kilometers. In a recent example, a pyrocumulonimbus cloud was recorded in southwest France, while similar clouds were reported during the Boston Bar fire in British Columbia last year. The clouds can produce violent wind gusts and lightning that can start new forest fires.
Written by the local model on 2026-08-21,
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Story summary
Canada is often affected by pyrocumulonimbus clouds, also known as fire clouds, during its wildfire season. These massive clouds form when large wildfires burn, releasing water vapor into the air that then cools and condenses into towering cumulus-like formations. In fact, Meteorologist Mike Fromm of the Naval Research Lab in Washington D.C. claims that Canada experiences more pyrocumulonimbus clouds than anywhere else in the world. These fire clouds can be over 200 kilometers wide, and are often seen hovering above dark plumes of smoke from large wildfires. When they grow to a certain size, they start behaving like thunderstorm clouds, producing strong, erratic winds and lightning that can make wildfires spread even faster.
Written for “Huge Wildfires Cause Massive Smoke” on 2026-08-31,
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The article presents a neutral, informative tone, providing explanations and expert opinions from both meteorologists without apparent bias or emotive language.
Written under an earlier scoring contract, which gave a paragraph
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Leaning score -0.05 for article 29 · logged 2026-07-30
You can only see these fire clouds during huge wildfires
Pyrocumulus and pyrocumulonimbus clouds are generated by wildfires and can worsen their spread
A huge fire in southwest France has generated the country's first recorded pyrocumulonimbus fire cloud.
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fire → see → cloud
Such clouds can only be seen during huge wildfires, and are often reported in Canada during wildfire season, most recently during the Boston Bar fire in B.C.
Here's how these special clouds form and how they can make wildfires worse.
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wildfires → see → B.C.
What do fire clouds look like?
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clouds → look → What
Pyrocumulonimbus or pyroCb clouds have been described as giant and cauliflower-like — so huge they can be seen more than 200 kilometres away.
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they → describe → ?
They're often seen hovering above dark plumes of smoke.
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They → see → smoke
They generally resemble the dark, fluffy-looking cumulonimbus thunderstorm clouds that they get their name from (along with "pyro" for "fire").
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they → resemble → fire
They first form as smaller pyrocumulus clouds that top out at five kilometres altitude.
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that → form → altitude
But fuelled by large wildfires, they can grow into pyroCb clouds, reaching more than a dozen kilometres above the ground.
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they → fuel → ground
A "monster pyroCb" in B.C. in June 2021 was measured by NASA for sending smoke up to 16 kilometres high and spreading across more than 160,000 square kilometres.
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pyroCb → measure → kilometres
How do they form?
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they → form → ?
The heat from a wildfire causes hot air to rise in an updraft, pulling moisture, smoke and even burning embers up with it.
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air → cause → it
Because the atmosphere is cooler higher up, at some point the vapour and smoke cools and spreads out, and the water condenses into a cloud above the smoke column.
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water → cool → column
While fire clouds are rare in Europe, they can appear by the dozens during wildfires in North America, according to NASA.
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they → appear → NASA
Mike Fromm, a meteorologist with the Naval Research Lab in Washington, D.C., says "Canada is probably the corner of the world that gets the most pyrocumulonimbus."
Why are they dangerous?
Fromm said when they grow large enough, pyrocumulonimbus clouds start to behave like thunderstorm clouds in other ways, generating strong, erratic winds and lightning.
They can grow high into the atmosphere, where it's cold enough to freeze the water droplets into ice.
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it → say → ice
Because cold air sinks, the air can drop suddenly to the ground, producing violent wind gusts called downdrafts.
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air → sink → gusts
The clouds also darken the sky, making visibility more difficult for firefighters.
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visibility → darken → firefighters
"It can truly turn mid-afternoon into nighttime conditions," Fromm said.
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Fromm → turn → conditions
But because smoke particles in these clouds limit the size of water droplets, their storms don't generate much rain alongside the lightning.
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storms → limit → lightning
Christy Climenhaga, a meteorologist for Environment Canada and former CBC climate reporter, said that lightning can start forest fires in new areas that hadn't yet started burning.
"They are something that are hard to deal with when you look especially at the fire suppression side of things because they can make the fire more unpredictable and more dangerous," she said in a 2023 CBC report.
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she → say → report
NASA reported that the monster pyroCb in B.C. in B.C. in 2021 produced nearly 113,000 cloud-to-ground lightning strikes, or an estimated five per cent of Canada's annual lightning all at once.
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pyroCb → report → lightning
PyroCbs can also disperse ash and smoke long distances by transporting it high into the lower stratosphere, where it can spread around the globe and stay in the atmosphere for months or years.
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it → disperse → months
