If something is a bolt from the blue, it is a complete and sudden surprise - like a bolt of lightning against a blue sky.
The prime minister's resignation was a bolt from the blue.
It was a real bolt from the blue when I bumped into my first ever boyfriend in the supermarket.
The announcement about redundancies was a bolt from the blue for the workers in the office.
Don't confuse it with
You can also use the phrase out of the blue to mean something which comes as a surprise.
His marriage proposal came out of the blue - but she said yes!
The London 2012 men's 100m final was a stunning race. Seven out of the eight finalists finished in under ten seconds, making it the fastest 100m final in history. Usain Bolt won gold in 9.63 seconds - the second fastest time in history. He also holds the world record for the fastest ever 100m, which he ran in a time of 9.58 seconds in Berlin in 2009.