Is it okay to visit Xian around 6th to 11th December? How cold will it get?

It will be dry and cold in December. The usual average temperature is about -3~6C. It may have snowfall sometimes. If you visit the city at that time, you need to prepare very warm clothes like down-jacket or overcoat. It is a little dangerous to visit Huashan at that time since the steps on the mountain may be slippery. It is also very cold on the mountain.