is december a good time to visit china?

TinaS

planning a trip to china in december. wondering if it's a good idea.

i know it will be cold. but i don't mind cold weather. i'm more worried about things being closed or not running.

will the great wall be open? i heard some sections close in winter.

are the trains running normally? or do delays happen because of snow?

also worried about air pollution. is december bad for that?

i'm thinking beijing, xi'an, and shanghai. about 10 days.

anyone traveled to china in winter? what should i expect? thanks.