also: よさめ
noun
night rain
Refers to rain falling at night. Both readings やう and よさめ are used, with やう being more common.
夜雨が降ると、翌朝の空気が澄んでいる。
When night rain falls, the air the next morning is clear.
旅先で夜雨の音を聞きながら眠るのが好きだ。
I like falling asleep to the sound of night rain while traveling.
Compound of 夜 (night) and 雨 (rain). The reading やう is the on'yomi, while よさめ is a kun'yomi-based reading.