Home Postcodes by state WA 6356 Postcode 6356 6356 is the postcode for 3 localities in WA: Hatter Hill, Lake King and Mount Madden. Localities with postcode 6356Hatter HillWALake KingWAMount MaddenWA Postcode 6356 State or territory Western Australia (WA) Localities 3 Council area Lake Grace Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6355 · Postcode 6357