sunshower
Rain falling while the sun is shining; a common weather phenomenon in Japan.
今日は照り雨で、虹が出た。
Today there was a sunshower, and a rainbow appeared.
Compound of 照り (teri, 'shining') + 雨 (ame, 'rain'). The exact historical derivation is uncertain, but the word transparently describes rain while the sun is shining.