Heavy rain and gales devastating parts of Italy have claimed two more lives, taking the overall death toll to at least 17.

A German tourist died on Friday when hit by lightning on the island of Sardinia while another person struck by lightning several days ago died in hospital, Italy's Civil Protection Agency said on Saturday.

A spokeswoman said 17 deaths related to the severe weather had been reported to the Agency so far.

Many of the victims to date have been killed by falling trees. Coldiretti, the association of Italian agricultural companies, said in a statement that gales had destroyed around 14 million trees, many in the far north.

People help to remove debris around destroyed yachts on the shore after a strong sea storm in Rapallo. Photo: Reuters

"We'll need at least a century to return to normality," it said.

Areas from the far northeast to Sicily in the southwest have been affected, with the worst damage in the northern regions of Trentino and Veneto - the region around Venice - where villages and roads have been cut off by landslides.

Many of Venice's squares and walkways have been submerged in the highest floods the canal city has seen in a decade.

The governor of Veneto, Luca Zaia, said the region's storm damage amounted to at least €1 billion. 

Angelo Borrelli, head of the Civil Protection agency, said Veneto had seen winds of up to 180 kph (112 mph), and that the situation there was "apocalyptic".

Deputy Prime Minister Matteo Salvini was due to visit the region on Sunday.

Fallen trees are seen in the water of Piave river near Belluno. Photo: Vigili del Fuoco