The best time to visit Koh Phayam is November through April, when the northeast monsoon keeps the Andaman side calm and the skies clear. This is also the cashew harvest season, which peaks in March and April. The island is at its most beautiful and accessible in these months, and most guesthouses and restaurants are open.
May through October is the southwest monsoon season — seas on the west coast can be rough and ferry services from Ranong may be reduced or cancelled in bad weather. Some businesses close for the season and the island empties considerably. Experienced travellers who like quiet and don't mind occasional rain can find good value and genuine solitude in the shoulder months of May and October.