Updated

An unusually high tide flooded most of Venice early Wednesday, forcing tourists and residents to wade through knee-high waters or take to improvised, elevated boardwalks set up in St. Mark's Square and other landmarks.

The waters came in before dawn and reached a peak of 56.6 inches above average sea level. City authorities said that put around 60 percent of Venice's streets and piazzas under water.

Wednesday's level was still far from last year's record 63 inches, Venice's worst flooding in more than two decades.

The tide receded during the day but the city said that more flooding is expected in coming days.

Northern Italy has been hit by snowstorms and cold temperatures that has shut down airports, idled trains and wreaked havoc on traffic in Milan and other cities.

Venetians are largely used to the "acqua alta" (high water) phenomenon, which occurs when strong winds from the south contribute to raise the sea level in the lagoon city.

The ANSA news agency reported some shops and ground-floor apartments were damaged by Wednesday's flood.

A system of movable barriers that would rise from the sea bed to protect Venice from exceptionally high tides has been in the works for years but will not be operational before 2014.