La Rochelle has a mild Atlantic climate — warm summers, cool wet winters, late springs. The city is on the same latitude as Lyon but with milder winters and breezier summers.
The summer high season runs from late June to late August: the town is busy with French and northern European holidaymakers, the marinas are full, and accommodation prices roughly double. Reserve well ahead for July and August. May, June, and September are the sweet months — warm enough to swim, quiet enough to enjoy a terrace lunch without queueing.
The big event is the Francofolies music festival in mid-July: a five-night French-language pop festival that has been the city's calling card since 1985. The Grand Pavois sailing show in late September fills the harbour with boats. The town is also nice in winter — restaurants stay open, the towers are empty, and the seafood is at its best.