rain that seems to keep a guest from leaving; well-timed shower
A poetic expression for rain that begins just as a guest is about to depart, as if to prevent them from going. Often used in a warm or slightly humorous context.
Just as I was about to leave, a well-timed shower started to fall.
やらずの雨のおかげで、もう少し話ができた。
Thanks to the rain that kept us from parting, we could talk a little longer.