Beihai has a subtropical climate with a long warm season and a mild winter. The best time to visit is October to April, when the typhoon season has passed, the heat is manageable, and the water is clear. October and November are particularly good: the sea is still warm enough to swim, the beaches are relatively uncrowded, and the bioluminescence season extends into these months.
Summer (June to September) is hot and humid, with typhoon risk from July onwards. Silver Beach is at its most crowded in July and August when school holidays bring visitors from across Guangxi and Guangdong. The water is warmest then, but the beach experience is less pleasant. Weizhou Island is worth visiting in any season; the diving is best when visibility is highest, typically October to December.