Venice is a city built in the water and so, as you would expect, in winter it rains. A lot. The two things every Venetian needs in winter are a pair of stivali di gomma (wellington boots) and an ombrello (and umbrella).
Piovada is the Venetian word for a heavy rain shower, such as you get in November through February. This is joined in the Venetian rain vocabulary by piovesina (fine rain) and piova fissa (persistent rain). The standard Italian word for rain is pioggia.
There’s a lovely idiom containing the word piovada, which is used to reassure people that something is easily fixed: basta ‘na piovada e neta tuto (literally, a heavy rain shower is enough to clean everything).