Find the word definition

Wiktionary
keep a weather eye open

vb. (context intransitive idiomatic English) to maintain a background awareness of something; to remain alert to changes without it occupying your full attention.

Usage examples of "keep a weather eye open".

The special responsibility, of course, is to keep a weather eye open for Sovbloc illegals and couriers-and so forth.

The special responsibility, of course, is to keep a weather eye open for Sovbloc illegals and couriers—.

I tipped him the wink and as he knew you were due he thought I'd better stay on shore to keep a weather eye open.

He or she would want to be awake, to plan the next atrocity and keep a weather eye open for pursuers.