Most people visit Italy between June and August. However, the best time to visit is in spring, from April to May, and autumn, from September to October, when the weather is good and the tourists are few. The sea is warm enough for swimming between June and September. Most Italians take their vacation in August, and many shops and restaurants are closed during this period. Or to see the lagoon city at its emptiest and most atmospheric, come in November, season of mists and acqua alta (tidal flooding: bring rubber boots) or January, between Christmas and Carnival. August is sheer insanity. Avoid it if at all possible.