come out of a clear blue sky

come out of a/the clear blue sky

To happen unexpectedly. She seemed so surprised by the news that it must have come out of a clear blue sky. You need to work hard—opportunities don't just come out of the clear blue sky.

See also: blue, clear, come, of, out, sky

come out of a clear blue sky

 and come out of the clear blue sky; come out of the blue

suddenly; without warning. Then, out of a clear blue sky, he told me he was leaving. My sister Mary appeared on my doorstep out of the blue, after years with no word from her.

See also: blue, clear, come, of, out, sky