Question

Out of the Clear Blue Sky suddenly and without any warning: totally unexpectedly

Accepted Answer

Out of the clear blue sky, he asked her to marry him. This late 19th-century expression is related to another saying, "a bolt from the blue" (see page 18). A bolt of lightning or sudden shower from a clear, blue sky would be unexpected. Sometimes this idiom is shortened to "out of the blue."

Idiom	Out of the Clear Blue Sky
Example	Out of the clear blue sky, he asked her to marry him.
Meaning	suddenly and without any warning: totally unexpectedly
Origin	This late 19th-century expression is related to another saying, "a bolt from the blue" (see page 18). A bolt of lightning or sudden shower from a clear, blue sky would be unexpected. Sometimes this idiom is shortened to "out of the blue."

Blue Sky Clear Bolt Asked Marry Suddenly Warning