noun
long spell of rain in early spring
Refers to the extended rainy period that often occurs around the time rapeseed flowers bloom, typically from late March to April in Japan. A seasonal word (kigo) used in haiku.
今年の菜種梅雨は長くて、なかなか晴れない。
This year's spring rain spell is long, and it just won't clear up.
梅雨 is the summer rainy season (June–July), while 菜種梅雨 is a shorter rainy spell in early spring.
Compound of 菜種 (rapeseed) and 梅雨 (rainy season), referring to the rainy period when rapeseed flowers bloom.