Holy Week in late March or April is by far the most important time to visit if you want to see the Moriones Festival — the week-long event peaks on Good Friday and Easter Sunday, and the island's population nearly doubles as Filipinos return from Manila to participate. Book ferries well in advance; accommodation around Boac fills up completely.
The dry season from November to May is the best time for beaches and island-hopping. June through October brings rain and the risk of typhoons; Marinduque sits in a moderately exposed position in the Philippine typhoon belt, and serious storms can strand visitors by closing the ferry routes. July and August are the wettest months. Year-round temperatures are warm, hovering around 27–32°C.