Home Postcode finder WA Mount Cooke Mount Cooke postcode WA Mount Cooke is a locality in Western Australia covered by postcode 6390. Postcode 6390 State or territory Western Australia (WA) Region Wa Subs 2 Gsr Add a free Mount Cooke business listing Be the first listing in Mount Cooke Common questionsWhat is the postcode for Mount Cooke?Mount Cooke, WA has the postcode 6390.What state is Mount Cooke in?Mount Cooke is in Western Australia (WA).Does postcode 6390 cover more than one suburb?Yes. Postcode 6390 covers 11 localities, so the postcode alone does not identify Mount Cooke. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.