bolt from the blue, a

Something completely unexpected or surprising; that which occurs without any warning. We always thought of Michael as a lifelong bachelor, so it was a bolt from the blue when he returned from his vacation sporting a wedding ring! News that they were going to dissolve our company came like a bolt from the blue. We're all still in shock from it. We all thought Grandma was healthy as can be, so her cancer diagnosis came like a bolt from the blue.

Fig. a sudden surprise. (Alludes to a stroke of lightning from a cloudless sky.) Joe's return to Springfield was a bolt from the blue. The news that Mr. and Mrs. King were getting a divorce struck all their friends as a bolt from the blue.

Also, a bolt out of the blue. A sudden, unexpected event. For example, Bill's dropping his life insurance was a bolt from the blue for his wife. This metaphoric term alludes to totally unforeseen lightning or thunder from a cloudless (blue) sky. [First half of 1800s]

COMMON If an event or a piece of news is, or comes like, a bolt from the blue, it is completely unexpected. A Foreign Office spokesman had described the coup as `a bolt from the blue'. Note: You can also say that something is, or comes like, a bolt out of the blue. Mrs Thomas says the arrest had come `like a bolt out of the blue'. Note: This expression usually describes unpleasant events or pieces of news. Note: This expression compares an unexpected event to a bolt of lightning from a blue sky. The expressions `out of a clear blue sky' and `out of the blue' are based on a similar idea.

A sudden, shocking surprise or turn of events.

A sudden, unexpected event, usually of a catastrophic nature. The term refers to a bolt of lightning or thunder that comes from a blue (cloudless) sky and hence is not anticipated. Although “blue” was a poetic allusion to the sky by 1700, the precise expression dates from the early nineteenth century. It appears in Thomas Carlyle’s description of chaotic events of the French Revolution: “Arrestment, sudden really as a bolt out of the blue, has hit strange victims” (1837).