Is Dec/Jan a decent time (I know it's not the best) to visit Beijing to do some sightseeing (Great wall, forbidden city, ming tombs, etc.) or is it too cold? Tempratures listed by weather.com seem cold but tolerable but I don't know if other factors such as wind, snow, pollution would make it difficult.

Wind, snow, overcast, rain, pollution..but 17 million people seem to endure
Beijing winters without too much problem.

I visited Beijing early Feb. 2005. I don't handle the cold very well and felt *really* cold at the Summer Palace with the snow, wind, and ice. On the plus side, there were very few tourists around in general.

Also, try to plan around Chinese New Year. It begins on January 26, 2009 and involves two weeks of festivities. The Chinese people get that time off for the celebration, so there will be crowds everywhere during that period.

Beijing's pretty dry, from the 2 winters I was there... and in general.. it is freakin' cold though. Would recommend mid-september through late october or mid-april through mid may.

The people are gritty and endure though.

Beijing is very cold and windy during this time. But also very dry--bring heavy duty moisturizers and hair conditioners. Snow is not common, and when it happens, it's usually only about an inch or less of very powdery stuff. It is possible you will not see any snow during a brief visit in winter. Ice is exceedingly rare. Pollution is not too bad on most days due to wind blowing it away, and clear blue skies are reasonably frequent. You will need full protection gear when you are outside--long underwear, warm socks and shoes or boots, lined gloves, scarf, hat, ear protection. The insides of hotels and public buildings are heated, often overly so (northern Chinese are surprisingly wimpy when it comes to dealing with cold weather). It's similar to Chicago winter but with much less snow. But not as cold as a Green Bay, WI winter (I used to live there!).

Very few tourists either international or domestic at this time, and hotel rates, etc. usually go down. Remember that daylight is short, and most tourist attractions will open later and close earlier. Consider 08:00-16:00 as your useable daytime.

Definitely try to avoid Chinese New Year and even up to one week ahead of it. Many attractions, small restaurants and shops, etc. will be closed, usually for 3 days but sometimes longer. During this time, many more Beijingers and migrants leave for other provinces to see family, than those coming in, so I don't think Beijing and its tourist attractions are particularly crowded during this time--in fact, just the opposite, at least by normal Chinese standards.

It helps if you have a flask of erguotou to keep your bones from freezing
in that bitter cold dry air.

If you are intelligent, unlike I was a few years back, you will not drink Yanjing during dinner, during the after-dinner poker game and then use said remaining Yanjing as a kind of chaser as you finish off a half liter of leftover erguotou (1 liter bottle at 6 RMB with 57% by volume). The resulting sickness and hangover is a painful painful lesson learned...

It is quite nice when eating a meal though with the old-school Chinese men in restaurants. Very cultural and certainly cleans the palate (while burning your throat) between bites. Hint: do not bother smelling it.

We visited Mutianyu in the summer, when the surroundings were green and lush. Pictures I've seen of the Great Wall in the winter are amazing with the snow covering everything and the solitude. Would love to visit, but is it much more difficult to get there in the winter? Is the weather particularly brutal in the countryside? I grew up not far from Chicago, so I know winters. However I've also lived in the South for a long time now and have turned into a bit of a weather wimp.

Also, we couldn't squeeze in Xi'an on our last visit. What's it like to visit in the winter? TIA.

One of our many special experiences was the Great Wall and tobagganing down at Mutianyu! Probably not operational in the winter. Slip sliding away....

The "countryside" in this case is more of a Beijing suburb or satellite since Mutianyu is not too far away. The photos with snow are nice, but rarely does it snow in Beijing or areas around, rather its very dry, so the landscape might be desolate (or have rugged beauty, you choose the term). Roads to Mutianyu are very well developed so it won't be tough to get there.

December can be really nice. As others have noted, it's a low pollution month. Furthermore, chances are, it won't be that cold. However, the mere thought of January makes me shiver. Thank goodness I was able to secure that extended "business" trip to Hawaii this January.

Thanks everyone, really helpful. Looks like Dec/Jan is doable, but not highly recommended. We will probably defer it to later in the year but in case we go, will have erguotou handy