The science behind fire clouds, fire thunderstorms, and fire tornadoes

Weather and wildfires share a close relationship. Certain weather conditions are known to ignite wildfires: High temperatures and low humidity dry out the landscape, lightning strikes can spark a flame, and fast-moving winds spread flames across nearby desiccated land.

But wildfires also spawn their own weather systems, including pyrocumulonimbus clouds—which NASA has called the “fire-breathing dragon of clouds” for the thunderbolts they hurl at Earth, fueling further blazes and sometimes even fire tornadoes.

Fire weather has contributed to the scale of several historic conflagrations, including the 2009 Black Saturday bushfires that burned more than a million acres across Australia, and the wildfires across the West Coast of the United States in 2020. Here’s what causes firestorms—and why they’re becoming more common in a warming world.

How firestorms get started

Firestorms form through a convective process, in which heat rises through the air. When a column of moist air over a

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