More than 6,200 hectares have burned in the Gironde region and the neighbouring Landes in the latest wildfire to erupt in a European nation as the continent swelters through a hot and dry summer.
The blaze forced the evacuation of about 10,000 people and destroyed at least 17 houses, according to firefighters.
A major highway near the city of Bordeaux was closed on Wednesday afternoon due to the fire raging nearby.
French Interior Minister Gerald Darmanin announced that more firefighters have been sent to the site in an effort to contain the fire.
In total, more than 1,000 firefighters, nine aircraft and two helicopters have been mobilised, he said.
The Gironde region was hit last month by major wildfires that forced the evacuation of more than 39,000 people, including residents and tourists.