Pierre Barnes, 12, Missing On French Island
Twelve-year-old Pierre Barnes vanished on Saturday after going for a bike ride on the island of Porquerolles, near Toulon on the Mediterranean coast.
Rescuers found one of his shoes on a coastal path on Sunday, alongside his bike with its chain off, it was reported.
His father Stephen, 57, from Grantham, Lincolnshire, told French television of his hopes that his son had survived the storm, the Daily Telegraph said.
Mr Barnes said: "I am certain he went off on an adventure on his bicycle but, in the forest, all the little tracks look the same.
"He is lost but he is a strong boy and I hope he found a place to sleep where there was not too much wind.
"It's difficult to say what you can do when you are cold and frightened."
More than 150 local volunteers are believed to have helped search for him on Sunday.
A spokeswoman for the Foreign Office said: "We can confirm that a British national has been reported missing in France.
"We are in touch with the French authorities and we are providing consular assistance."