From which month does the rainy season in Hangzhou end?

The rainy season in Zhejiang lasts from late April to early May and ends in late May.

Every year from late April to early May, cold air from the north and warm air from the south meet in South China, forming a quasi-static front in South China. By the end of May, the influence of warm air was strengthened, and the quasi-static front moved northward to Jianghuai area, becoming the quasi-static front of Jianghuai (also known as Meiyu front).

Because the warm air from the south carries a lot of water vapor, when it meets the cold air mass, it will produce a lot of convection activities. Because of the equal influence of cold and warm air during this period, the front stays in Jianghuai area.

Typical plum rains generally "enter plum blossoms" in the middle and late June, and bloom in early to mid-July. Meiyu refers to the rainy days before plum blossom, which generally starts in mid-April and lasts for about half a month.

Chi Meiyu:

Contrary to early plum rain, late plum rain is usually called late plum rain in meteorology. There are more opportunities for late meiyu than early meiyu. Because the solar term is already late when the late Meiyu begins, once the warm and humid air flows northward, it will be very powerful.

At the same time, the solar radiation is also relatively strong, and the air is prone to strong convection after being heated, so there are often thunderstorms and showers in the later period of Meiyu. People also call this kind of Huang Meiyu "Huangmei". The duration of the late Meiyu is generally not long, with an average of only about half a month. However, the rainfall of this plum rain is sometimes quite concentrated.

Baidu Encyclopedia-Meiyu Season