Several fires have raged in recent days in the southern region, fanned by winds and kindled by parched vegetation, including Tuesday's just north of the port city of Marseille.
"The fire is clearly receding, it is no longer advancing," Marseille firefighting chief Lionel Mathieu said.
The flames had swept through 750 hectares (1,800 acres) of land, affecting at least 70 homes of which 10 had been destroyed, but there had been no human casualties, Mathieu added.
Some 700 firefighters were on duty on Wednesday morning, with helicopters dumping water from the air to help their colleagues on the ground.
Local authorities said some 15,000 residents of Marseille's 16th district in the north of the city, hit by flames on Tuesday afternoon, were now allowed out of their homes.
But it was still too early for some 400 of them who were evacuated to return home.
The blaze had started in an area north of Marseille late Tuesday morning after a vehicle caught fire.
"There's every reason to believe that we're heading for a high-risk summer," warned Interior Minister Bruno Retailleau on Tuesday evening at a press briefing with firefighters in Marseille.
In just a few hours, the fire had spread over 700 hectares, leading to the closure by mid-day of Marseille Provence airport, France's fourth-largest in terms of passenger numbers, located to the north of the city.
Traffic partly resumed around 19:30 GMT on Tuesday, but local authorities warned the airport could be closed again on Wednesday to allow for more airborne fire-fighting.
According to satellite images, the smoke plume stretched out to sea for around a hundred kilometres.
High-speed train traffic in Marseille resumed on Wednesday morning after a fire-related interruption, while local train traffic remains severely disrupted, railway operator SNCF announced.
Meanwhile, down the Mediterranean coast in an area near the city of Narbonne, firefighters fought to stamp out a blaze that had spread across 2,000 hectares since Monday.
Scientists say human-induced climate change is increasing the intensity, length and frequency of extreme heat that fuels forest fires.
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