Fujian sits in the humid subtropical monsoon belt, averaging 17–21°C across the year. The reliable sweet spot is October through early December: clear, cool, dry, low-typhoon, ideal for Xiamen cycling, tulou hiking, and the Jiuqu (Nine-Bend) bamboo rafting at Wuyishan. Spring (March–April) is pleasant but rainy, and May–June brings the meiyu plum-rain season of sustained drizzle and high humidity.
Summer is the season to pad the itinerary. Typhoons peak July–October, with August–September carrying the highest probability of rerouted flights and ferry suspensions to Gulangyu and Meizhou; late storms occasionally arrive into early November. Coastal south Fujian — Xiamen, Quanzhou, Zhangzhou — usually stays above 10°C through winter and remains walkable, but Wuyishan and the inland highlands turn properly cold and can see frost.
If the trip anchors on a festival, time it accordingly: the Lantern Festival (Quanzhou and Zhangzhou put on the flagship nights, usually February), Mazu's Birthday on Meizhou Island (23rd day of the 3rd lunar month, late April / early May), the Qingming–Guyu tea-picking window in Wuyishan and Anxi (early–late April), Mid-Autumn's Bo Bing mooncake dice in Xiamen, and Mazu's Ascension Day back on Meizhou in the 9th lunar month (October).