Hi Wolverine23 and welcome to TripAdvisor,
There is an early cold snap hitting Shanghai right now, but it will be warming back up this next week.
As for your Shanghai weather in December, check out the MSN weather averages:
You can see it stays above freezing, barely, if the averages hold true. It is humid in Shanghai all year around, so some say that makes the cold more penetrating. Dress warmly in layers with scarves and gloves of some sort. The wind chill temperature will definitely be below 0C.
Carry an extra pair of shoes for all travelers in case one pair gets wet in an odd slushy snowfall which might occur. No one really shovels this wet snow very much. It sits there until it melts.
oh dear, seems like not such a good idea for kids to go then??? :(
I cannot reply to your concern about weather in Nanjing or Wuxi mid-December, but Shanghai in all the years I've been here has never felt too cold or clammy in December. Jan, usually, and Feb too, can get a bit uncomfortable and damp, but mid-Dec is still fine--a very enjoyable time of the year. I never seem to bundle up then, only layers of warm sweaters or a jacket+sweater (don't forget possibility of rain). Yet if you're used to very temperate or tropical climate at home, then Shanghai late fall may "feel" colder for you than people habituated to its climate.
As for children, I'd not worry at all: plenty of little ones run around here mid-Dec very happily, and none too slowed down by the temperature, which in my view is acceptably cool, not "cold." But that, of course, may be subjective: a check online to annual Shanghai (and Nanjing/Wuxi) temperatures, when compared to your home climate's, may reassure you more specifically.
Your children will need more than just layers of warm sweaters; most kids here have a warm winter jacket available by then, and a cap. Plus the usual kids' winter clothing: pants, warm socks, tights, long-sleeved shirts, etc. You probably don't need anything down. But again, that's for Shanghai; not sure for elsewhere.
The other good news: you'll probably be able to purchase anything for the children you might have forgotten, and would probably enjoy a one-time visit to one of Shanghai's many shopping havens; there are also, apparently, inexpensive little children's "marts," where much can be had quite reasonably. I'd pass you that info, but don't have a child that small. Friends do.
I'm sure you'll have a wonderful trip with your family.
You need something warm in Mid December, although most locals consider December be part of fall, not really winter; If you are from south Asia, you must understand that locals are familiar with weather pattern so they always prepare warm and heavy coat incase some thing coming down from Siberia.
These days in Shanghai , the weather's so tremendously cold , it suddenly drop from 28 degrees to 5 degrees, which rarely happened in past 10years. But usually, in Dec, the temperuture is 5 degrees or so.
I saw the temperature on various websites and it's around 18 degrees today (12 Nov) but the forecast for next week is only 11 or 13 degrees and 4 or 5 degrees (lowest)! I am from the tropics and this is my first time to a place that is below 15 degrees, do I need to bring thermal wear? is a sweater + outerwear + 2 layers of long sleeve top warm enough? thanks!!
You dress according to your activity level. If you are going to sitting or standing around outside, then you might want to wear heavy layers. If you are going to be walking a lot, on the go, so to speak, then you can dress in shirt/blouse, sweater and unlined windbreaker.
Although the permanent residents might be used to this December cold, us tropical people from Southeast Asia and Miami Beach, FL, find this weather very cold. Gloves are a necessity at these temperatures around 0-5C. Consider a woolen scarf too, just in case it is very windy day.
In the best case weather, you can eliminate the sweater from your ensemble.
thanks for your help! may I know if places like the museum or Yuyuan will have heater or air-con but blowing hot air ?
winter - early -
nah - in my experience - came a few days late. the earlier weather was warmer than usual, hence the "cold" snap seems worse.
fond memories of drizzle and single digit temps in early - not mid - nov--- try pouring concrete in these temps.
its downhill from here...