Rangiroa sits just south of the equator and is warm year-round, but the two seasons are distinctly different.
May to October is the dry season and the best time to visit. Temperatures are cooler (23–28°C), humidity drops, and the trade winds keep things pleasant. The water is at its clearest for diving, and the dolphin pods at Tiputa Pass are reliably present. June to August brings the most comfortable days, though nights can be genuinely cool and the sun sets early.
November to April is the wet season: hotter, more humid, and prone to afternoon squalls that come and go quickly. Cyclones are rare but possible between December and March — Rangiroa has suffered serious damage before. The reef fish are more active in warmer water, and visibility is generally still good between rain events.
The lagoon is warm enough to swim in comfortably all year (around 27–29°C). Wetsuit requirements for diving are minimal — a 3mm shorty is enough even in the coolest months.
Avoid August school holidays if crowds concern you; even in a place this quiet, the pensions fill up.