expression, noun
a bolt out of the blue; a sudden and surprising event
Idiomatic expression used for an event that is completely unexpected, like a thunderclap from a clear sky. Often used in formal or literary contexts.
彼の突然の辞任は青天の霹靂だった。
His sudden resignation was a bolt out of the blue.
そのニュースはまさに青天の霹靂で、誰もが驚いた。
The news was truly a bolt from the blue, and everyone was shocked.