What month does the rainy season start?

Meiyu days often appear in June and July every year. The annual rainy season basically lasts from mid-June to early summer in mid-July. The middle and lower reaches of the Yangtze River in China refer to a period of continuous rainy weather within the range of 28°-34° N east of Yichang, or from Jianghuai Valley to a narrow area in southern Japan. In early summer, there are often long rainy days in the Jianghuai basin. At this time, the utensils are easy to be moldy, so it is also called "moldy rain" or "mildew" for short; It is also called "Plum Rain" or "Huang Meiyu" because plums in the south of the Yangtze River are yellow and ripe.

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.

The middle and lower reaches of the Yangtze River in China are usually rainy from mid-June to early July every year. In the past few days, the sky has been gloomy and the precipitation has been constant, sometimes big and sometimes small. Therefore, there is a popular proverb in southern China: "Rain hits Huangmei's head and there is no sun for forty-five days." Continuous rain, high temperature and high humidity are the main characteristics of plum rain.