Home Postcode finder WA Mount Observation Mount Observation postcode WA Mount Observation is a locality in Western Australia covered by postcode 6302. Postcode 6302 State or territory Western Australia (WA) Region Wa Subs 2 Gsr Add a free Mount Observation business listing Be the first listing in Mount Observation Common questionsWhat is the postcode for Mount Observation?Mount Observation, WA has the postcode 6302.What state is Mount Observation in?Mount Observation is in Western Australia (WA).Does postcode 6302 cover more than one suburb?Yes. Postcode 6302 covers 23 localities, so the postcode alone does not identify Mount Observation. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.