February — Carnival. The Carnival of Viareggio is reason enough to visit in late January or February. The four parade Sundays draw enormous crowds; book accommodation weeks in advance. The floats are spectacular in daylight but even more dramatic after dark.
June to August — beach season. High summer is busy and expensive. The beach establishments are packed, accommodation prices peak, and the promenade buzzes until midnight. If you want beach culture and don't mind crowds, this is the time.
May, September, and October — the sweet spot. The sea is warm enough to swim but the crowds have thinned. Accommodation is cheaper and easier to find. The Liberty-style architecture is easier to appreciate when the promenade isn't wall-to-wall with beach umbrellas and summer bodies.
July and August — Puccini Festival. Torre del Lago, 5 km south, hosts open-air opera performances in a lakeside theatre. Tickets should be booked ahead; performances sell out quickly.
Winter. Viareggio is quiet out of Carnival season. Most beach establishments close, some restaurants reduce hours, but the town remains liveable and the day-trip possibilities (Lucca, Pisa, the Apuan Alps) are excellent.
The climate is mild — warm summers, cool winters, with the Apennines blocking the worst of the cold air from the north. Rainfall is spread through autumn and spring; summer is reliably dry and sunny.