4. Mei-Yu in Taiwan

In terms of climate, May and June are called the "Mei-Yu Season" in Taiwan. During this period the weather is mostly cloudy to rainy, but occasionally it will be clear. The Mei-Yu season in Taiwan is caused by the strengths between the continental cold air mass and the Pacific warm air mass often coming to equilibrium in southern China, Taiwan, and the Okinawa region, creating a stationary front (so called Mei-Yu front). Low pressure disturbances often take place in these areas and along with them intermediate to heavy thundershowers, which bring abundant rainfall to the Taiwan area.

The name Mei-Yu originates from the fact that the continuous rain season in June and July in south of Yangtze River, China is also the mellow season for plum fruit. Since in this kind of continuously rainy season thing will easily mold, it is also called "moldy rain" (in Chinese the words "mold" and "plum" are both pronounced "Mei").