n. 1. Eyes that can tell what the weather will be. Grandfather's weather eye always tells him when it will rain. 2. Eyes ready or quick to see; careful watch. Usually used in phrases like "keep a weather eye on", "open", or "out for". Mrs. Brown kept a weather eye on the children so they wouldn't hurt each other. Keep a weather eye out for Uncle George at the store. Keep a weather eye open for deer. The police have a weather eye out for the robbers.
Compare: LOOK OUT.