"We are frightened, this reminds us of the floods of 1994," Garessio mayor Sergio di Steffano told reporters
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.
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.
A leading local official from Cuneo, Giovanni Russo, called on residents to stay away from the water except in case of absolute necessity.
Schools were shut in several provinces of the area.