expression, godan verb (-ru)
to stop raining
Common expression for rain stopping or letting up. The verb 上がる here means 'to lift' or 'to clear'.
See also: 上がる (あがる)
午後には雨が上がるでしょう。
The rain will probably stop in the afternoon.
雨が上がったら出かけよう。
Let's go out when the rain stops.