Trang's Andaman coastline has a pronounced dry season from November to May and a wet season from June to October, when the sea is rough and boat services to the islands are reduced or suspended. November to February is the most reliable period — calm seas, good visibility, and pleasantly dry weather. March and April are hot but still dry.
Avoid June to September unless you are visiting solely for the town: the seas are dangerous for island trips and many island bungalows close entirely. The clam season at Hat Pakmeng runs from October to February, and the annual Valentine's Day underwater wedding on Ko Kradan (14 February) draws visitors from across the province. The town's night market and food scene is active year-round.