local rainfall; isolated showers
Refers to rain that falls in a very limited area, often at the top of a mountain or in a specific spot, while surrounding areas remain dry. A somewhat poetic or descriptive term.
At the top of the mountain, a local rain was falling, but the foot was clear.
天気予報では晴れだったのに、駅前だけ私雨に遭った。
The forecast said sunny, but I got caught in an isolated shower just in front of the station.