I would like to visit Yunnan on 21 to 28 Sept 2012, how is the rainfall & temp there ?

During that time, it is still the rainy season of Yunnan. The average temperature during 21st-28th of Sep. is about 18 C or a little higher. Besides, the temperature may drop quickly along with the rain. You need take along long-sleeved shirt, thin coat and a raincoat. To pay attention to the weather report when you want to be out may help you a lot.