I will trip with my wife at Kunming in first of september I wish ask the weather.

The latest wether forecast says that it will rain from Sep. 1 to Sep. 6 and on Sep. 7, it will be cloudy. The temperature is reported to range from 16℃ to 25℃. Considering all, I suggest you wear long-sleeved shirt and pants. Prepare a light jacket as well as simple rainy gear.