"My dog died out of the blue."
I am trying to say "My dog unexpectedly passed away."
Very broadly speaking, the idea with 'out of the blue' is that something happens unexpectedly. But I think there is also a sense that something comes or arrives. It sounds OK to say eg Out of the blue, I got a letter from my high school sweetheart.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
Very broadly speaking, the idea with 'out of the blue' is that something happens unexpectedly.
But I think there is also a sense that something comes or arrives.
It sounds OK to say eg Out of the blue, I got a letter from my high school sweetheart.
It doesn't sound OK to say eg Out of the blue, I fell and broke my leg.
Your example of My dog died
My dog just up and died. (Colloquial)
I think "out of the blue" requires an element of surprise as well.