out of the blue
1
occurring without prior warning
- The invitation to the party came out of the blue, and I couldn't believe my luck.
- He quit his job out of the blue, leaving everyone at the office stunned.
- They decided to move to another city out of the blue, surprising all their friends.
- She received a phone call out of the blue from a childhood friend she hadn't spoken to in years.
- The sudden storm arrived out of the blue, catching many people unprepared.