Hi, I am planning a trip to Huangshan Mountains at the end of december (29 Dec 2014).

In late Dec. the temp in the mountain would be 10 – 25F. It’s very cold there. And sometimes may be snowing. If you go there in 29th Dec, it wouldn’t be crowd for the Xmas has passed.

Tips: take warm clothes (down jacket, sweater, boots) and be careful when you climbing the mountain.

It is hard to tell you the cost for two day trips from Shanghai, because it depends on ur transportation methods, accommodation choice, dining level and others.