"The fire is not completely under control but we are winning the fight," Lieutenant-Colonel Michael Bernier, the civil security officer leading the emergency effort in Bormes-les-Mimosa, the scene of the worst blaze, said. "Things are going in the right direction but new fires are starting caused by gusts of wind."
Some 12,000 people had been moved to safety on Tuesday and 1,500 spent Wednesday night in emergency accommodation while others chose to sleep on the beach rather than return to campsites.
Prime Minister Edouard Philippe praised the 6,000 emergency service and military personnel fighting the flames on a visit to an emergency shelter on Wednesday.
The fire had not spread during the night but gusts of wind caused new blazes to flare up from time to time on Thursday.
A Canadair waterbomber, provided by Italy, was sent to the island of Corsica after fires started again near Biguglia, in the north of the island, following an appeal for more resources from regional president Gilles Simeoni.
Flare-ups were also reported on social media at Carros near Nice.
More than 7,000 hectares of vegetation have been burnt in four days and investigators are trying to establish the causes.
Negligence by members of the public, for example discarding cigarette ends, has been blamed but there are also suspicions of arson.
Two teenagers, one 16 and the other 17, were still in detention at Martigues, near Marseille, on Thursday after being arrested the day before in possession of matches, lighters and binoculars, according to France Info radio.
One person who had been arrested earlier was also still in detention in relation to a fire in Peynier, near Aix-en-Provence, while two others had been released.
Many of the fires are “of criminal origin” and the “activity of arsonists” has to be stopped, Renaud Muselier, president of the Provence regional council, told FranceInfo.
Environmental campaigners have warned that similar wildfires can be expected in the future as summers become hotter and drier due to global warming.