Bellinzona benefits from Ticino's mild climate. Spring and autumn are the best seasons for visiting — temperatures are comfortable, the light is good for the castles and old town, and the Saturday market is in full swing. Summer is warm to hot; the castles provide shade and the valley catches a breeze in the evenings.
The Rabadan carnival in February is one of the largest in Switzerland — a week of costumed processions and parties before Lent that draws participants from across Ticino and over the Italian border. If you happen to be there during Rabadan, the city transforms completely. The rest of the year Bellinzona is calm to the point of quietness.