Plan to visit Jiuzhaigou at 26th Dec this year

HI...possible by walking all the way for the valley? what is estimate temperature during the month of december in degree celcius..?

what's your recommendation of days to stay in there if i also want to visit hualong and if i arrived in Jiuzhaigou around 5pm by bus and back to chengdu again by bus. 2night stay sufficient ?? and where is best stay around in the valley?