I once ran across a Japanese term for this. Searching for it again, I encountered a long list of terms from all over the world, some of them beautifully whimsical. Many of them involve weddings: of gypsies or poor people or ghosts or witches; of foxes, wolves, monkeys, jackals, or bears—or of a fox and a bear, or a tiger and a fox, or a fox and a raven. The Japanese term is kitsune no yomeiri, or fox wedding. (Though my recollection was of a term that somehow combined sun and rain . . . but I must be wrong.)
My most memorable sunshower was in Madison, Wisconsin, one afternoon when I was home alone, after class or maybe it was a rare weekend without roommates, watching Singing in the Rain on TV in my upstairs flat. At the very moment that Gene Kelly goes swinging around the lamppost, the skies opened up with both a downpour and brilliant sunshine. The coincidence was perfect!