Out of the blue

Meaning

Unexpectedly.

Usage

Describes surprises.

Origin & History

Origins and dates here are approximate summaries. Many idioms have disputed or unknown origins, and not every date has been checked against a historical dictionary, so treat specific dates and stories as a starting point rather than a citation.

From the older phrase 'a bolt from the blue', meaning lightning from a clear sky.

In use since the 19th century.