Day - around 23 degrees
Morning and night - about 5-8 degrees cooler

Jean plus T-shirt plus one light jacket, running shoe plus slippers are all you need for the trip

Yunnan is a BIG place, so it depends on which part you are referring to. The northern part seems to have four seasons in one day almost year round. The southern part is hot most seasons. The eastern part is much like the rest of China, although a little cooler in summer and a little warmer in winter.

Thanks. I plan to go to Dali and Lijiang so not sure whether to pack much summer clothing. Since it's at a high altitude, it'll probably get fairly cold in the evenings right?