out of a clear blue sky

Idioms  

1. Also, out of the blue. Without warning, suddenly, as in Her offer to help us with the fundraising came out of a clear blue sky, or We got a check from Aunt Ruby out of the blue. These metaphoric terms allude to something dropping unexpectedly from the sky. [Late 1800s] Also see out of nowhere.

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Example Sentences

“You can have one come out of a clear blue sky.”

From Los Angeles Times

The sun shone into Anya’s face out of a clear blue sky.

From Literature

Devastation struck out of a clear blue sky for Yana Stepanenko.

From Seattle Times

The first FRBs struck astrophysicists like thunderbolts out of a clear blue sky; no theory had predicted their existence.

From Scientific American

But the trauma of the terrorist attacks two decades ago — which came out of a clear blue sky to kill nearly 3,000 Americans — has not faded, and some warn against turning the page prematurely.

From Washington Post