Zhenyuan has a humid subtropical climate typical of eastern Guizhou. Summers are hot and wet (June to August) with heavy rainfall and lush vegetation; winters are mild and damp rather than cold, rarely dropping below freezing. Spring (March to May) is the most rewarding season: lower humidity than summer, the Wuyang River at a good level for boat trips, and the tea gardens in harvest. April in particular is ideal — the spring tea harvest is underway and the river valley is green after winter.
Autumn (September to November) is the second-best choice: clear skies, moderate temperatures, and fewer domestic tourists than the summer peak. The Chinese national holidays (October Golden Week) bring crowds and higher prices but also a festive atmosphere in the old town. Avoid July and August if you dislike heat and humidity; the gorge can be uncomfortably hot in the middle of summer.