1
general::
Phrase(s): *out of nowhere
appearing suddenly, without warning. (*Typically: appear ~; come ~; materialize ~.) • A huge bear appeared out of nowhere and roared and threatened us. • Suddenly, a truck came out of nowhere. • Without warning, the storm came out of nowhere.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Suddenly, unexpectedly, as in That anonymous letter turned up out of nowhere. It is often put as come out of nowhere, as in Their team came out of nowhere and won the state championship. This term uses out of in the sense of "from," and nowhere in the sense of "an unknown place." For a synonym, see OUT OF A CLEAR BLUE SKY.
American Heritage Idioms