Hi I'm planning to visit friends in the Shanghai/Nanjing area in December /January. Climate, temps?

The average temperature in Shanghai is 41 to 46 °F from December to January. In Nanjing, it is 36 to 41°F. It's winter time. But it isn't as cold as those northern cities. Thick jacket, sweater and thick trousers are ok. If you are afraid of coldness, you may wear down jacket, sweater, wollen underpants and outwear trousers.

Thanks Stella.