Summer (June to August) is the most popular time to visit Hämeenlinna, when Häme Castle and Aulanko Nature Reserve are fully open and the lake is navigable by boat. The summer boat service connecting Hämeenlinna to Tampere along the Poet's Way waterway runs from June to August — a full-day scenic journey through the lake district that is one of Finland's classic travel experiences.
Winter offers a different appeal: cross-country skiing in Aulanko, the possibility of walking on the frozen lake, and the Nordic winter light at its most dramatic. The museums stay open year-round. Spring and autumn are quieter and can be cold, but the forest colours in October are excellent.
The city's main festival is the Sibelius Festival, held in September, which brings classical music performances to the castle and other venues in what is an unusually intimate setting for a music festival of its quality.