Venice gets about 750 mm (roughly 30 inches) of rain a year, but its defining water risk isn’t rainfall total at all — it’s acqua alta, the periodic flooding caused by a combination of high tides, storm surge from the Adriatic, and low atmospheric pressure that pushes water into the lagoon and through the city’s canals and streets. Autumn and winter are the highest-risk months, when strong sirocco winds from the southeast can pile up water against the city faster than it can drain. Heavy rain falling at the same time as one of these tidal surges compounds the problem significantly, as happened during the severe November 2019 flooding that submerged much of St. Mark’s Square. Because the danger here comes from the interaction of weather and tide rather than rain alone, radar imagery showing an approaching storm is one piece of a warning system that also includes tide forecasts from Italian and local Venetian authorities.
Learn more: Flash Flood Warning Signs on Radar · Open the full Rain Map