Home Postcodes by state WA 6640 Postcode 6640 6640 is the postcode for 5 localities in WA: Cue, East Murchison, Lake Austin, Reedy and Weld Range. Localities with postcode 6640CueWAEast MurchisonWALake AustinWAReedyWAWeld RangeWA Postcode 6640 State or territory Western Australia (WA) Localities 5 Council area Cue; Murchison Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6639 · Postcode 6642