We are travelling in HK on Jan. 23-27,2015. Is it still cold by then?Should we were heavy jackets?

Well, according to the previous statistics, the temperature during that period of time is 57.2 F to 71.6 F. It's warm. This period mainly contains cloudy days. T-shirts, light jackets and jeans are enough for you to prepare. So it's not necessary for you to bring your heavy jackets.