Calculations by Víctor Resco de Dios, professor of forest engineering at the University of Lleida, and doctoral researcher Simon Schütze show the fires generated 1,800 terajoules (TJ) of thermal radiation. The 'Little Boy' atomic bomb dropped on Hiroshima in 1945 generated 63 TJ.

"Nobody is prepared to face fires of this magnitude," Professor Resco said.

Firefighters continue to battle the blazes today (Wednesday) as an ongoing heatwave threatens containment efforts across the region.

The Ávila fire, with a perimeter exceeding 180 kilometres, is expected to become the largest wildfire in modern Spanish history after burning more than 50,000 hectares. In Madrid, the fire perimeter spans 250 km, with 34,000 hectares destroyed.

Fernando Castedo Dorado, forest engineering professor at the University of León, described the fire behaviour as unprecedented.

"The images show extremely high intensity," Professor Castedo Dorado said. "Crown fires were igniting tree canopies and advancing rapidly. That indicates exceptionally high heat output. This combination of fires is a completely unprecedented situation."

Experts attribute the extreme fire behaviour to heavy fuel loads, continuous forest cover and severe heatwave conditions.

The blazes mark an unprecedented summer for Spain in 2026. The season has already recorded the deadliest wildfire of the century, following 14 deaths in Los Gallardos, Almería, and prompted the first Level 3 civil protection emergency declaration for a wildfire in Spanish history.