Spring (mid-February to early April) is the famous rapeseed season, when the valley floors turn yellow between the old villages. The beauty is real but the crowds are equally real — tour groups, weekend visitors from Shanghai and Hangzhou, and domestic photographers fill the village lanes from 8am on weekends. If you're visiting during peak season, arrive on a weekday, stay for at least two nights, and start each morning before the buses arrive.
Autumn (September to November) offers the second-best visiting window: the rice harvest, the russet foliage on the surrounding hills, and a much more manageable crowd level. The villages look different but still beautiful. Winter is cold and sometimes misty, which some visitors find atmospheric; summer is hot and humid, with the tea fields in full growth but the famous yellow fields absent.