Why does it rain every year during the Dragon Boat Festival?

Because this time is the rainy season.

In the middle and lower reaches of the Yangtze River in China, Taiwan Province Province, south-central Japan, South Korea and other places, there will be continuous rainy weather in June and July every year. Because it is the mature period of plums in Jiangnan, it is called "Meiyu", and this period is called Meiyu season. In the rainy season, the air humidity is high and the temperature is high, so clothes are easy to get moldy, so some people call the rainy season "moldy rain". After the rainy season, the weather began to be dominated by the Pacific subtropical high and officially entered the hot summer.