What's a fire cloud?
A fire cloud, or pyrocumulonimbus if you want to try saying that five times fast, is a rare bit of weather that shows up when intense heat from something like a wildfire or a volcanic eruption drives smoke, ash, and water vapor up into the atmosphere.
In other words: it's a fire that makes its own thunderstorm. 🤯
How can a wildfire make a thunderstorm?
The fire throws off enough energy to shove a column of smoke, ash, and water vapor straight up.
If the atmosphere is unstable, the smoke keeps going up, up, up, high enough to punch into the stratosphere, the second layer of the atmosphere.
As the plume climbs, the air expands and cools. The moisture in it condenses, and boom: pyrocumulonimbus.
The cloud throws lightning (which starts more fires) and whips up wind (which spreads the fire already burning).
How high the smoke goes
The fire feeds itself
That's what makes these clouds more than a curiosity. The storm a fire builds turns around and hands the fire new lightning and new wind, so the thing keeps restarting itself.
Where the fires are
About 325,000 people have left their homes across France and Spain. More than 63,000 of them are in Madrid, Toledo, and Ávila.
- Associated Press, via PBS News: the first recorded pyrocumulonimbus in France.
- ITV News: interviews with Dr. Francesca Di Giuseppe (ECMWF) and Víctor Resco de Dios.
- AFP and CNBC: Capt. Nicolas Braz on fires that can't be managed.
- CNN: evacuation figures for France and Spain, July 27, 2026.