Home Postcode finder SA Willowie Willowie postcode SA Willowie is a locality in South Australia covered by postcode 5431. Postcode 5431 State or territory South Australia (SA) Region SA Outer Suburbs Add a free Willowie business listing Be the first listing in Willowie Common questionsWhat is the postcode for Willowie?Willowie, SA has the postcode 5431.What state is Willowie in?Willowie is in South Australia (SA).Does postcode 5431 cover more than one suburb?Yes. Postcode 5431 covers 14 localities, so the postcode alone does not identify Willowie. Browse other postcodes in South Australia, or widen the search to every Australian postcode.