Tahiti's climate is split into a hot, wet summer (November–April) and a cooler, drier winter (May–October). The cooler months are the better travel window — daytime temperatures stay around 27°C, humidity is bearable, the trade winds are reliable, and the cyclone risk drops to near zero.
The big event of the year is the Heiva i Tahiti — a four-week festival of Polynesian dance, song, sport and outrigger canoeing in July, with finals on Toata Square in central Papeete. Book accommodation well ahead if you're coming in July. The Hawaiki Nui Va'a outrigger canoe race in early November is the other unmissable cultural event for any traveller curious about contemporary Polynesian sport.