July and August are the obvious season — the beaches fill up, the funfair runs at full tilt, and the weather is at its best, which on this coast still means a decent chance of rain. Late September is the Elvis Festival weekend, and the entire town is fully booked from months ahead.
Spring and autumn are quieter, often surprisingly bright, and the surf at Rest Bay is best. Winter is genuinely worth a visit if you like raw weather — Atlantic storms regularly bury the harbour breakwater in spray, and the seafront cafés stay open year round.