Italy is the next country to face adverse weather that has affected much of central and eastern Europe, claiming at least 22 lives.
The Italian meteorological service has warned that heavy rainfall and thunderstorms are expected in the coming days, with strong wind gusts, lightning and hail also possible.
Red alerts are in place for the Emilia-Romanga and Marche regions in the north of the country, where the heaviest rain is forecast for tomorrow.
Less severe warnings are in effect for many other areas.
There are reports of flooding in the central city of Pescara.
Storm Boris has brought high winds and unusually heavy rainfall to parts of Austria, the Czech Republic, Germany, Hungary, Poland, Romania and Slovakia since last week.
At least 22 people are dead.
Although the weather seemed to be stabilising in several places, the ground remained saturated and rivers were overflowing, with authorities asking people to remain cautious.
Two big cities in Poland - Opole in the south and Wroclaw in the west - are still awaiting the flood wave and there are concerns that the dykes there could break.
Prime Minister Donald Tusk announced additional government aid for those in Poland hit by the storm, bringing the total sum to two billion zloty (€468 million).
Polish police reported that three more people had died as a result of Storm Boris, raising the toll in the country to seven.
Police chief Marek Boron announced the updated figure at a televised crisis meeting.
At least two of the new victims were discovered in the southwestern district of Klodzko.
"The body of an 82-year-old man was discovered in a car," police spokeswoman Wioletta Martuszewska said.
"A couple of hours later, mountain rescue services said the body of a man had been found near a riverbed," she added.
There were unofficial reports of additional victims elsewhere, but police cautioned against publishing unverified information.
"We ask everyone not to report false information about the number of flood victims in the media," police said on social media.
A new victim was also reported in Austria.
An 81-year-old woman was Austria's fifth victim of the floods, a police spokesman said.
The fire brigade found the woman's body in her flooded home in Lower Austria, the worst-impacted province in the Alpine nation.
Storm Boris has also caused the deaths of seven people in Romania and three in the Czech Republic, according to the latest tallies.
In Austria, 26 communities were cut off and with the weather improving, "we are discovering the scale of the disaster", Lower Austrian governor Johanna Mikl-Leitner told reporters.
In the Czech Republic, more than 60,000 homes were still without electricity, mainly in the country's northeast, and 500 people were evacuated yesterday evening, including children.
The largest Czech retention basin, the Rozmberk pond in the country's south, has been overflowing its banks.
Experts have said climate change caused by greenhouse gas emissions generated by human activities is increasing the frequency and intensity of extreme weather events such as torrential rains and floods.
Andreas von Weissenberg, of the International Federation of Red Cross and Red Crescent Societies (IFRC), said studies to determine whether climate change is linked to these events are expected in the coming months.
Mr Von Weissenberg said local Red Cross teams were helping the rescue and evacuation efforts, including attending to people's "emotional and mental health".
The floods, he added, have been "branded as historic" but warned that "climate change has a way of moving the goalposts".
