A lifeless body of 60-year-old man was discovered in a parking of Mandelieu-la-Napoul town, bringing the total number of people killed due to torrential rainfall to 18, the daily Le Figaro said on its website.
Earlier in the day, a 90-year-old man previously reported missing in Antibes was found. He had been hospitalized on Saturday night, the regional daily Nice Matin said.
Due to lack of information about his situation, police and fire officers were seeking for him, believing he was struck by floods, it added.
Heavy rains lasting three hours on Sunday overnight triggered strong floods that swept Alpes-Martimes department where three people were still missing.
French President Francois Hollande, who visited the affected towns with Interior Minister Bernarc Cazeneuve, said the status of natural disaster would be recognized at Wednesday's cabinet meeting.
He also pledged to pay compensations within three months to help finance damages.