Venice has been flooded and five people have died as storms have swept across Italy, with gale force winds and heavy rain leaving rivers dangerously swollen.

Italy’s national Civil Protection Agency issued multiple weather warnings as the weather lashed much of the country on Monday.

Local authorities shut schools and urged people not to travel unless absolutely necessary.

In Venice, the high tide hit a maximum of 156 centimetres on Monday – the fourth-highest level recorded. City officials said up to 75 per cent of the lagoon city was under water.

Venice frequently floods when high winds push in water from the lagoon, but Monday’s levels were exceptional.

St Marks Square was also under water. Photo: Getty

Access was barred to Venice’s famous St Mark’s Square, which was heavily flooded. Transport officials closed the city’s water bus system to all but outlying islands.

Veneto regional governor Luca Zaia said the flooding might reach the levels of the 1966 flood that struck both Venice and Florence.

Elsewhere, two young people died south of Rome when a tree hit the car they were travelling in. Another person was killed and several injured in the nearby town of Terracina after howling winds brought down scores of pine trees.

“Stay at home. Do not go outside for any reason,” Terracina Mayor Nicola Procaccini told residents.

A 21-year-old man was killed by a falling tree as he was walking in Naples. In the northern region of Liguria, a woman died after being struck by debris blown off a building.

Dozens of trees were reported uprooted across Rome and many parks and tourist sites were closed, including the Roman Forum and Colosseum. Further south, the ancient Roman city of Pompeii was shuttered because of the blustery conditions.

With further bad weather forecast, dozens of towns and cities said they would keep their schools closed on Tuesday, including in Rome, Venice, Verona and Naples.

-with AAP