A firenado can spin up inside a large wildfire and fling burning debris

Wildfires do not simply spread outward across a landscape; under the right conditions they generate their own violent weather. When intense heat, turbulent surface winds, and a large burning area combine, a spinning column of flame and ash can rise from the blaze and briefly behave like a tornado. Scientists call these vortices fire whirls, and the largest examples have uprooted trees, hurled burning material far beyond a fire’s edge, and produced wind speeds strong enough to earn a rating on the same scale used for ordinary tornadoes.

How a Rotating Column of Flame Takes Shape

A fire whirl begins as an ordinary whirl of wind, often made visible only by the smoke curling inside it. Intense rising heat from a fire creates a strong updraft, and when that updraft meets converging surface winds, the two can combine into a tight rotating column. As the eddy contracts, it behaves like a tornado-like vortex, drawing in embers, ash, and combustible gases that keep the rotation burning from within. Researchers classify these features into a handful of types, ranging from whirls that stay centered directly over the burning area to ones that form downwind or over open ground next to an uneven fire front. Most fire whirls are modest: roughly 10 to 50 meters tall, only a few meters wide, and gone within minutes as the fire’s heat output shifts.

Temperatures and Wind Speeds Inside the Vortex

The largest fire whirls are a different matter entirely. Some grow to more than a kilometer tall, sustain internal wind speeds above 200 kilometers per hour, and persist for more than 20 minutes before dissipating. Inside the burning core, temperatures can reach roughly 1,100 degrees Celsius, hot enough to consume material that would otherwise resist a conventional flame front. That combination of heat and rotation gives large fire whirls the strength to uproot mature trees 15 meters tall or more. They also help fires spread in ways firefighters find especially dangerous: the rotating column can lift burning bark and embers high enough that wind aloft carries them well beyond the active fire line, igniting new spot fires ahead of crews working to contain the original blaze.

The Deadliest Fire Whirl on Record

The most catastrophic known fire whirl followed the 1923 Great Kanto earthquake in Japan, when a citywide firestorm engulfed sections of Tokyo. Conditions in the Hifukusho-Ato area produced a fire whirl of such scale that it killed an estimated 38,000 people in about fifteen minutes, a toll that remains without parallel in the historical record of this phenomenon. The event illustrates how a firestorm large enough to generate its own weather system can turn a mass evacuation site into a lethal trap, since victims that day had gathered in an open space specifically to escape the surrounding flames, according to the account preserved on Wikipedia’s fire whirl entry.

California’s Carr Fire Produced an EF3-Rated Tornado

Modern instrumentation has allowed meteorologists to measure these events with far more precision. On July 26, 2018, the Carr Fire near Redding, California, spawned a fire tornado that the National Weather Service later rated EF3 on the Enhanced Fujita scale after surveying the damage. The vortex killed four people, injured six others, and produced peak wind speeds estimated at 143 miles per hour, making it the most powerful tornado on record to strike the state of California regardless of whether it originated from a thunderstorm or a wildfire. The Carr Fire event is widely cited by fire behavior researchers as the moment public attention shifted toward treating large fire whirls as a distinct and serious hazard rather than a visual curiosity.

Meteorologists Have Begun Issuing Warnings for Fire-Generated Tornadoes

Two years after the Carr Fire, the National Weather Service issued its first-ever tornado warning for a pyrocumulonimbus cloud, the towering, fire-fed storm system that formed above the Loyalton Fire near the California-Nevada border in August 2020. Three fire tornadoes were confirmed from that event, two of them rated EF1. More recently, on July 12, 2025, the Deer Creek Fire in San Juan County, Utah, produced a strong, nearly stationary fire tornado rated EF2 that damaged a fire engine belonging to the Bureau of Land Management, though no injuries were reported. Each of these events pushed forecasters to treat fire-generated rotation with the same operational seriousness as severe thunderstorms.

Why the Danger Extends Well Beyond the Flames

Fire whirls have proven hazardous even to people and equipment operating away from the fire itself. During the 1871 Peshtigo Fire, a fire whirl destroyed the community of Williamsonville, Wisconsin; the site is preserved today as Tornado Memorial County Park. In more recent decades, aviation has emerged as another point of vulnerability: in May 2015, a firefighting aircraft near Cold Lake, Alberta, encountered a fire whirl and lost control, colliding with terrain and killing the pilot. Because these vortices can appear suddenly over an active fire and dissipate just as quickly, fire crews and aerial firefighting teams now factor the possibility of a fire whirl into their planning whenever conditions include strong surface winds, uneven terrain, and a large, actively burning fire front.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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