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Related to keep a: keep busy
keep a weather eye open
An instruction to monitor someone or something, often because the person or thing in question may turn out to be dangerous. I think Tom's a thief, so keep a weather eye open around him. I'd keep a weather eye open with this storm that's brewing—we may have to evacuate.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
keep a/one's weather eye open
To keep watch; stay alert.
See also: keep
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.