Hi,
Generally speaking, the best time to visit HK is between October and March. It is getting hot and humid in June and there are sometimes rains and thunder. Yet it is still not so bad. Travellers can get great discounts while shopping in summer. And what is good for you is that you can take your daughters to enjoy water activities in Ocean Park and Disneyland that is only available in summer. Do prepare umbrella and overcoat and sunblock.