May to october is the rainy season of this area. Whenvever you go to Zhongdian, thick clothes to keep warm is necessary. Summer is supposed to be the best time to visit. Temperature varies greatly in daytime and night during summer and autumn. Chose sunny days to make a hiking to Mei Li Snow Mountain. Or you may not see it from any angle if the weather is not good. The time is fine, but you should still well prepare. Bring hat, sun glasses and so on. Protect you cameras if it rains. Enjoy your time there.