A sunshower or sun shower is a meteorological phenomenon in which rain falls while the sun is shining. A sunshower is usually the result of accompanying winds associated with a rain storm sometimes miles away, blowing the airborne raindrops into an area where there are no clouds, therefore causing a sunshower. Sometimes a sunshower is created when a single rain shower cloud passes overhead, and the Sun's angle keeps the sunlight from being obstructed by overhead clouds.

Source: Wikipedia