We're planning to visit hong kong and macau from 9th-13th dec. what will be the climate roughly and what kind of clothes should we carry?

It will be cloudy during that time in the two places, according to the latest weather forecast. The temperature will range from 10C to 20C. Considering all, I suggest you take along T-shirt, coat and jeans. If you are from hot place, take a cardigan to keep warm in cool nights.