The weather here in June is usually warm and sunny, perfect for outdoor activities. Sometimes it can be a bit rainy, so you might want to bring an umbrella just in case.
As for the Dragon Boat Festival, it's a traditional Chinese holiday celebrated on the fifth day of the fifth month of the lunar calendar, usually in June. People often eat zongzi, a kind of sticky rice dumpling, and watch or participate in dragon boat races. It's a great time to experience Chinese culture and traditions.
I hope you and your family have a wonderful trip here!