Summer is peak season, roughly late June through August. The Charlottetown Festival runs through the summer at the Confederation Centre, and Victoria Row comes alive with patio diners until late. The island's beaches are swimmable in July and August, when the Gulf of St. Lawrence warms to comfortable temperatures.
September and early October are arguably the best time to visit. The summer crowds thin, the countryside turns red and gold, and the oyster harvest is at its most intense. Restaurants are easier to get into and the mood is pleasantly unhurried.
Winters are cold and quiet. The island effectively shuts down between November and April for tourism, though Charlottetown functions normally as a city.