Actually there is no bad moment to come to Hong Kong 😉 But there are two things that you might want to take into account when planning your move.
First of all, the school year starts end of August, so it makes sense if you come as a family to arrive in July and give yourself some time to settle in before school starts. As the school year ends by the end of June, you’ll see many expat families leaving Hong Kong in the beginning of July and you might can benefit from the fact that they leave behind great houses, furniture and helpers. On social media I see lots of house clearance or move out sales in June and July, which could be a great opportunity for anyone looking for second hand furniture. And the recommendations for great helpers are numerous.
Secondly, from a weather perspective, I would suggest that September/October are the best months. Hong Kong has 4 seasons (so don’t think it is always hot and steamy here), and September starts what I call the second part of the summer or beginning of autumn. The humidity is lower, less rain than the months before, still warm temperature, but not too hot and more blue bright skies. Good temperature to explore the city without being soaked after just a walk from the MTR to your house and the right moment to enjoy the outdoor sport opportunities Hong Kong has to offer.