At least three people were killed and thousands of others displaced after torrential rains poured over the northern Italian region of Emilia Romagna, local authorities said on Wednesday.
The heavy rains caused some 14 rivers to overflow, flooding streets and homes and causing severe disruptions to train traffic.
At least 5,000 people have been evacuated from the area, Minister for Civil Protection Nello Musumeci said.
Authorities are warning residents in the areas affected that the downpour could continue for another 12 hours.
"The emergency isn't over at all ... the rescue operations are complex and could put the rescuers in danger," Titti Postiglione, deputy head of Italy's Civil Protection Agency, told national broadcaster RAI.
Two weeks ago, similar weather conditions caused at least two deaths and severe damage in the same region.
Musumeci said the government was closely following the situation and has already earmarked €10 million (about $10.8 million) for rescue efforts.
Italy has been suffering from prolonged periods of drought in recent years, but experts say other extreme weather events, like storms and floods, are also becoming more frequent due to climate change.