A prolonged spell of rain — rain that continues for several days without stopping.
長雨のせいで畑の土がぬかるんでいる。
The prolonged rain has made the fields muddy.
今年の長雨は作物に被害を与えた。
This year's long spell of rain damaged the crops.
霖（ながあめ）が数日間続き、川の水位が上がった。
The nagaa ame (prolonged rain) continued for several days and the river level rose.