Parts of the mountainous area, which is located east of the city of Foggia and forms the 'spur' of the Italian boot, have suffered the heaviest rainfall registered in 80 years with more than 60cm (two feet) falling over the course of recent days, the equivalent of three quarters of the usual annual rainfall.
More than a 1,000 people had to be evacuated from campsites. At least 11 regional roads were unpassable because of the water level and there were severe delays on local train services.
The dead man was named as Antonio Facenna, 24, a farmer who had disappeared on Wednesday evening after going out in heavy rain to check on his animals.
His corpse was recovered on Saturday by rescue workers.
Another man, Vincenzo Blenxs, 70, was still unaccounted for on Saturday evening.