Plum rain

The East Asian rainy season, also called the plum rain, is caused by precipitation along a persistent stationary front known as the Meiyu front for nearly two months during the late spring and early summer in East Asia between China, Taiwan, Korea and Japan. The wet season ends during the summer when the subtropical ridge becomes strong enough to push this front north of the region. These weather systems can produce heavy rainfall and flooding. In China, the term “plum rain” was used for the rain in the fourth and fifth lunar month. It specifically refers to the historical belief that, when the plums turn yellow and fall at the south of the Yangtze in the fourth and fifth months, the moisture that evaporates from the plant turns into rain.