westonia postcode wa Home ›› Postcode Finder ›› WA ›› Westonia Westonia local listingsThe suburb of Westonia is located in WA and has a postcode of 6423. Free westonia business listing! 1Westonia Primary SchoolCnr Gold & Diorite Streets 08 90467051 View more business listings in westonia Search and find other Postcodes in Western Australia or widen the search to Postcodes in Australia.