Jacket or coat for children like 1 and 2 year old in Feb in HK

Hi, I am visiting HK this Feb and I understand it will be average 17 deg C. So I am bringing my children to visit HK. But what should they wear at that age? Normal jacket will do? Anyway they do not afraid of cold, cos in aircon room of 24 Deg C they still need to ON the fan to slp.