Almost 1,000 people had to leave Corsica during the night, with 2,000 hectares of scrubland destroyed, though no human casualties were reported.
Dry conditions have fuelled fires in recent weeks.
A man suspected of starting five fires in Bastia, a town with a population of 40,000 in the island's northeast, was arrested late Friday, an official said.
At Cap Corse, the most northerly point where the fire had spread overnight into Friday, the situation has been stabilised but the blaze remains rampant in the Sisco commune.
"It's hell," Christian Burchi, a 50-year-old Sisco resident said late Friday. "We tried to extinguish the flames with two buckets of water and a ridiculous hose. Everywhere is burning."