In brief
Hundreds of thousands were evacuated as wildfires near Bordeaux spawned pyrocumulonimbus, or fire‑generated thunderstorm, clouds that pump embers far into the atmosphere. Scientists explain the phenomenon occurs when extreme heat makes air rise, condensing into towering cumulonimbus clouds that can even produce lightning. Burned regions across Europe are now facing more of these deadly conditions after a dry summer marked by record heat and strong winds. Climate change is expected to raise the frequency of such fire‑storms, posing new challenges for firefighters.
Wildfires in Bordeaux aggravate with fire‑generated thunderstorms
Tens of thousands of residents were ordered to leave the Gironde region in the French city of Bordeaux after massive wildfires ignited forests and raised the temperature of the surrounding air to extreme levels. The heat has created towering pyrocumulonimbus – a cloud type that behaves like a thunderstorm only driven by the fire itself.
As the blazes push up hot air, the warm column rises and cools, causing water vapour to condense into a cumulonimbus cloud. These clouds can carry embers and ash kilometers away and, in some cases, produce lightning that sparks new fires.
French fire‑fighting authorities say the phenomenon has not been seen before in France and warn that it complicates firefighting efforts. Covering an area bigger than the original blaze, pyrocumulonimbus clouds can spread flames in unpredictable ways.
Europa’s summer has been marked by unusually high temperatures, gale‑force winds and a severe lack of rainfall, conditions that create dry, tinder‑rich landscapes. Climate‑change models forecast that such fire‑storm events are becoming more likely as heatwaves grow longer and hotter.
Last year’s bushfires in Australia's Black Summer and California’s 2021 summer drew similar images of towering smoke plumes. Experts described those clouds as “fire‑breathing dragons” that tossed embers thousands of metres high, suggesting that what is now happening in France is part of a broader trend of increasingly violent and unpredictable wildfire behaviour.
Fire agencies predict the current blaze in Gironde could burn for several months, with firefighting resources stretched thin against both the fire itself and the associated thunderstorm cloud. Residents are urged to keep safe and listen to evacuation orders as fire crews work to defend the region from a wildfire that could change how storms are formed on Earth.
