Arugam Bay's surf season runs from April through October, with the peak from May to August when the Indian Ocean southwest swell is most consistent. This is when the guesthouses fill up, the beach shacks stay open late, and the place has its characteristic energy. July and August are the busiest months.
November to March is the off-season. The northeast monsoon brings rain and rough seas — the surf breaks are messy and the bay loses most of its visitors. Many guesthouses close entirely. The upside is that those who stay have the place nearly to themselves and pay much lower prices.
Temperature is warm year-round, hovering between 27 and 32°C. Humidity is high in the wet season but tempered by sea breezes during the surf months.