Photos released by firefighters showed flames raging through pine forests, sending clouds of dark gray smoke soaring into the sky.
More than 60 square kilometers (23 square miles) have burned in the Gironde region and the neighboring Landes in the latest wildfire to erupt in a European nation as the continent swelters through a hot and dry summer.
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 mobilized, 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.
France is this week in the midst of its fourth heat wave of the year as the country faces what the government warned is its worst drought on record. Temperatures in the south of the country are expected to reach up to 40 degrees Celsius (104 degrees Fahrenheit).