Home Postcodes by state NSW 2103 Postcode 2103 2103 is the postcode for Mona Vale, NSW. Localities with postcode 2103Mona ValeNSW Postcode 2103 State or territory New South Wales (NSW) Localities 1 Council area Northern Beaches Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 2102 · Postcode 2104