Xiamen has a subtropical climate and is warm year-round. The best months are October to December: temperatures are mild (20–25°C), humidity drops, and skies are clearer than in summer. Spring (March to May) is warm and green but brings persistent overcast and drizzle. Summer (June to September) is hot and humid, with typhoon season running from July through September — storms occasionally disrupt ferry services to Gulangyu.
Winter (January to February) is the least-visited season; it is mild by Chinese standards (12–18°C) and rarely cold enough to be uncomfortable. The Gulangyu ferry queues are longest on summer weekends and national holidays, when domestic tourism peaks; if you visit in that window, take the first morning ferry and walk toward the far end of the island.