Statistically, it happens every two years. It starts as snow storm, but it takes some time for the snow flakes to stick to the ground. After all, this is not a climate known for long winters.
It used to be different in the 16th century, though. And still, statistically, the Lagoon freezes, at least in part, every five years. And in 1929, the whole Lagoon froze, and also the canals in Venice.
This is a very special experience, which is beautiful at first but it can be difficult to handle in case the snow doesn’t melt within the next hour or so. This happens every 3-4 years on average, and Venice will look white for a few days. In December 2017, we were so lucky to witness it once again. Below is a special video of this snow, and you will also listen to the bells of San Marco. It was shared by a Venetian artisan store owner, Perlamadre Design (find them here).