Six killed as downpours swamp Italy's Tuscany

There had been fears that the River Arno could flood the historic city of Florence after nearby towns were swamped by the southern edge of Storm Ciaran but the high water point passed in mid-morning on Friday without major incident.

Monia Monni, regional councillor for civil protection, confirmed the latest death toll, adding that one person was still missing.

"The situation is still very critical," especially in Campi Bisenzio, a town about 15km north-west of Florence where water levels were still high, she told Reuters.

"(Elsewhere), the water has drained away but there is mud and the devastation that an event like this leaves behind", Monni added.

About 190 people have been forced to leave their homes, including 150 who live in Campi Bisenzio.

The Italian government declared a state of emergency and allocated an initial 5 million euros ($A8.2 million) to help the worst-hit areas.

About 48,000 people in the region had no electricity, Deputy Prime Minister and Infrastructure Minister Matteo Salvini told a news conference.

Tuscany president Eugenio Giani said the region had never had so much rain in such a short space of time.

"What happened overnight in Tuscany has a clear name: CLIMATE CHANGE," he wrote on social media site X.

Another person, a firefighter, was missing in the northeastern Veneto region, the local governor was quoted as saying by Sky TG24.

Weather alerts remained in force in a number of Italian regions, with some schools closed, after a week in which the country has been lashed by strong winds and heavy rain.

Storm Ciaran was driven by a powerful jet stream that swept in from the Atlantic, unleashing heavy rain and furious winds that have already caused heavy flooding in Northern Ireland, parts of the United Kingdom, Belgium, the Netherlands and France.

Australian Associated Press