Firefighters battle an ‘explosive cocktail’ of wind and flames in southwestern France.

LA TESTE-DE-BUCH, France — More than 2,000 firefighters from around France were battling raging wildfires on Tuesday that have burned nearly 80 square miles of parched forest in the Gironde area of the country’s southwest and forced over 37,000 people to evacuate in the past week.

In the small town of La Teste-de-Buch, near the popular vacation destination of Arcachon Bay, a temporary firefighting headquarters was buzzing. Fire trucks raced and forth as helicopters and water-dropping planes flew overhead and officers reviewed color-coded maps of the flames.

While temperatures fell overnight as cool ocean air pushed the heat wave further to the northeast, the firefighters’ efforts have been hampered by strong gusts of wind, arid conditions and scorched trees that have sent burning embers through the air, further spreading the flames.

“Climate conditions are crazy,” said Matthieu Jomain, a spokesman for the regional firefighter unit. “It’s an explosive cocktail.”

“The area happens to be a real powder keg,” he added.

The huge clouds of gray and red smoke that billowed from the fires had reached all the way to Bordeaux, about 30 miles northeast, on Tuesday. A burning smell lingered in the air there, and health authorities recommended that residents — especially vulnerable people, like those with respiratory ailments — stay inside and limit intense physical activity.

Another wildfire was burning further inland, near the town of Landiras. Local authorities said in a statement on Tuesday that “the situation remains very unfavorable” in the area, where firefighters battled flames overnight and many roads have been closed off.

A man was still in police custody on Tuesday in connection with the blaze; prosecutors in Bordeaux have opened an arson investigation over suspicions that it had been intentionally set.

At the firefighting base in La Teste-de-Buch, trucks chopped down vegetation to clear a stretch of land and create a natural barrier to the fire. In another area, firefighters had dumped white sand along a roughly mile-long stretch.

Empty buildings and houses lined the asphalt road leading to the base. Only a handful of buildings have been damaged or destroyed by the blaze and no deaths have been recorded so far. Authorities have been preventively evacuating thousands of vacationers and residents who were not immediately threatened but might potentially be in the fire’s path.

Ronan Léaustic, a local official in Arcachon, told reporters on Tuesday that “it’s a strategy that we have adopted since the beginning” to avoid last-minute, panicked rushes to flee.

Nearly half of those displaced were evacuated on Monday, when leaping flames and billows of thick smoke moved closer to Arcachon Bay, a tourist hot spot famous for its oysters and sandy beaches that draws hundreds of thousands of vacationers every summer.

The fire destroyed five campsites around the nearby Dune du Pilat, Europe’s tallest sand dune. Authorities have closed access to the Dune du Pilat and traffic jams clogged the entrance to the Arcachon Bay after sections of highway leading to Bordeaux were closed to facilitate evacuations, upending plans for thousands as France’s summer vacation season is in full swing.

Patrick Davet, the mayor of La Teste-de-Buch, warned on Tuesday that the fire was “an enemy that never sleeps, that moves, that gives you no respite.”

“The fire is contained in some places, but it is not yet under control,” Mr. Davet told the BFMTV news channel.

The Bassin d’Arcachon Zoo in La Teste-de-Buch started evacuating animals as the fire has drawn dangerously close to the facility.

Zoo staff and workers and veterinarians from around the country acted “tirelessly to extract as many animals as possible, until the last moment, while the nearby forest was in flames,” the French government said in a statement.

About 10 of the zoo’s 850 animal’s died because of heat and stress, but 363 of them — all of those that could be easily transported — were safely evacuated. Most of them were taken in specially-designed crates and trucks to a nearby zoo in the suburbs of Bordeaux.

Around about 380 animals were kept at the zoo “for safety reasons,” the French association of zoological parks said in a statement.

Constant Méheut reported from La Teste-de-Buch, and Aurelien Breeden from Paris.