What to wear in Hong Kong during dec. 21-26, 2016 weather forecast?

We are going there with my husband & 3 children- ages 5, 1 years old & 7 months old. & 2 aunties. We don't know what to wear on this dates esp. To my kids? If thick jacket.We do not have an itinerary yet.
Could you please make recommendations for land arrangement in HK? We only book our hotel through internet. Any suggestion please.tnx - tin from Phils.