At night the mercury drops down to minus 20 Degrees Celsius. The days are clear and already 50 kilometers North of Beijing the sky turns blue. In this area chestnuts are grown and this is the only connection point with Christmas in Beijing. Christmas is of course not a Chinese festival, and it is here about on the same spiritual level than Helloween. But some people wish each other Merry Christmas in Beijing, and sometimes even take it as an opportunity to be a little bit less rude to each other. That's nice.
The region around the Shuyiyuan Dafoshan Area is nice for a Christmas walk. The trails lead through the villages and chestnut plantations and in the North West you have a very nice view on some sections of the Great Wall. You will not see any tourists here and the only people you meet are local farmers. The trail marked on the map below is about 12 km long. It is a bit tricky to find, but if you want to follow it by yourself I can send you the GPX file which is tracking a route (to use it you will need a real GPS, not a smart phone).