The sirens indicated that the tide was again expected to exceed 130 centimetres (50 inches), enough to bring the salty, dirty water back into the already-swamped UNESCO city's historic centre.
On Tuesday, the highest tide in 50 years ripped through the historic Italian city, peaking at 1.87 metres (six feet).
As authorities on Thursday prepared to assess the extent of the damage to Venice's cultural treasures, such as St Mark's Basilica where water had invaded the crypt, locals remained defiant.
“It's my living, what can I do?” Stefano Gabbanoto, 54, replied when asked why he was opening his newspaper kiosk knowing he would have to close up soon.
He said he would continue to sell the colourful plastic high boots stacked in bins around the kiosk even once it was shut.
Under the arches of the Ducal Palace, a newly married couple from Hong Kong posed for photos and video in the chilly morning sun.
“This was planned a long time ago so we couldn't change it,” groom Jay Wong, 34, said. His bride, Sabrina Lee, “looks cold,” he admitted.
“Actually this is a good experience,” Wong said. “It's an adventure.”
Prime Minister Giuseppe Conte was set to meet Venice's mayor and emergency responders before visiting businesses affected by the tide.
On Wednesday, Conte called the flooding “a blow to the heart of our country”, with the government expected to declare a state of emergency over the natural disaster.
Mayor Luigi Brugnaro has estimated the damage at hundreds of millions of dollars (euros), while several museums remain closed to the public.
Banksy's 'shipwrecked girl' mural in Venice after being partly submerged. Photo: AFP
Tuesday's “acqua alta,” or high waters, submerged around 80 percent of the city, officials said.
Only once since records began in 1923 has the water crept even higher, reaching 1.94 metres in 1966.
A 78-year old was killed by an electric shock inside his home.
Venice is home to a mere 50,000 residents but receives 36 million global visitors each year.
A massive infrastructure project called MOSE has been under way since 2003 to protect the city, but it has been plagued by cost overruns, corruption scandals and delays.
All photos: Marco Bertorello/AFP