Palau sits just north of the equator and has a warm, humid climate year-round with temperatures hovering between 27–32°C (80–90°F). The main distinction is between the dry season and the wet season, though neither is extreme.
November to April is the dry season and the most popular time to visit. Seas are calmer, visibility underwater is at its best (often 30+ metres), and the boat rides to the Rock Islands are smoother. December through February in particular are peak months — book accommodation and dive operators well in advance.
May to October is the wet season. Rain is frequent but typically arrives as short afternoon downpours rather than all-day grey weather. Seas can be choppier, making some boat trips less comfortable. On the upside: fewer tourists, lower prices, and the islands are even more lushly green. Experienced divers often prefer the wet season — currents can be stronger, which brings in more pelagic life.
Typhoons are possible but Palau sits somewhat south of the main typhoon belt and serious storms are relatively rare.
One thing to be aware of: manta ray season at German Channel runs year-round, but whale shark aggregations are most reliably seen in the wet season (June–August) around certain reef passes. If specific marine life sightings are a priority, research current conditions before booking.