Weather: It is hot and sunny with high humidity. The average low and high temperatures are 23 °C (73 °F) and 33 °C (91 °F). There are occasional downpours of rain, with about 18 days of rain throughout the month. The chance of a typhoon is 30% or less.
Clothing: Wear summer clothes and sun protection.
If you are a pollen allergy sufferer, be aware many flowers bloom in June in Hong Kong: African lily, Chinese quinine, Chinese hibiscus, pavetta, moth orchid, etc. If needed, please prepare a mask or take some medicine.
During the summer months, hiking in the mountains or shopping in a market street are good options. During inclement weather, the fine museums are places to go.
Dragon Boat Festival falls on June 9, 2016. Dragon boat races are held in about ten sites in the Hong Kong region. The races are an international event, and these races as well as parades and other festival activities are events that tourists can go see.
The Science Museum is mainly a children's museum though adults enjoy the exhibits as well. It is next to the History Museum, so both can be visited on the same trip. On Wednesdays, entrance to both museums is free. There are generally lines and crowds of children on Wednesdays.
Temple Street night market is a great place to hang out in the evenings. There are a variety of souvenir and low-cost products to choose from, and the street is easily accessible. You can dine outside in the street during the evenings. The food is economical by Hong Kong standards.
June is a low season travel month for HK. The weather is not pleasant, but the prices of hotels and flights are attractive. However, the Dragon Boat Festival draws the attention of hundreds of tourists every year. It is advisable to book in advance if you plan to visit during the festival.