On Friday morning, police were searching for a missing person in Perosa Argentina, a small town southwest of Turin.
According to initial reports, the man is a 70-year-old who fell into the Pellice tributary of the Po river, after a road collapsed. He was reportedly trying to help his horses when he got swept away.
The floods forced the closure of many roads, schools and businesses in the Piedmont and Liguria regions near southeastern France, which has also been hit by heavy rain.
Production has been halted at the Ferrero factory in Alba, which produces Nutella and Ferrero Rocher among other chocolatey treats, due to fears over the high level of the nearby Tanaro river.
Most bridges in Turin have been closed due to safety worries, as the Po rose to a metre above its designated safety level.
A red alert warning, the highest level, is still in place in Liguria until at least midday.
A total of around 400 people have been evacuated from their homes in Piedmont; 250 in Cuneo and 150 in Turin, while a further 200 have been evacuated in Liguria.
The presidents of the two regions said they would ask for a "state of natural disaster" to be put in place. This is different from the "state of emergency" which was put in place after the central Italy earthquakes earlier this year and is used only for disasters affecting the country on a national level.
Prime Minister Matteo Renzi visited Turin on Thursday to meet members of the Piedmont region's Civil Protection Department and local authorities. Renzi said: "The emergency phase is not over; no one can breathe a sigh of relief just yet."
Italian television channels showed footage of the Tanaro river bursting its banks and cutting in two the town of Garessio in Cuneo province near the tiny Mediterranean principality of Monaco.
"We are frightened, this reminds us of the floods of 1994," Garessio mayor Sergio di Steffano told reporters.
Flooding on November 5 and 6, 1994, left 70 people dead. No casualties have yet been reported from Thursday's storms.
"We have shut all the bridges, factories and schools. The bars and shops in the (town) centre are flooded. The main road is shut, we are cut off from the world," di Steffano said.
Isolated hamlets have been made inaccessible by the flooding and road closures.
A leading local official from Cuneo, Giovanni Russo, called on residents to stay away from the water except in case of absolute necessity.