Baiu (called also "tsuyu" and written also as "黴雨" [meaning 'rain of molds']) is a rainy period from May to July every year which is typical meteorological phenomenon seen in a wide area covering Japan excluding Hokkaido and Ogasawara Islands (Bonin Islands), the southern part of Korean Peninsula, coastal area of People's Republic of China including south and center China and Taiwan.
梅雨（ばいう、つゆ。黴雨とも）とは、北海道と小笠原諸島を除く日本、朝鮮半島南部、中華人民共和国の華南や華中の沿海部、および台湾など、東アジアの広範囲において見られる特有の気象で、5月から7月にかけて毎年巡って来る雨の多い期間のこと。