Mortlake, Australia offers 1 beach perfect for sunbathing, surfing, swimming, and more. Mortlake, New South Wales, Australia, is known for its proximity to the historic Yaralla Estate and the scenic Parramatta River. The best time to travel to Mortlake, Australia, is during the summer months of December to February, when the average air temperature is around 25°C (77°F) and the water temperature is approximately 21°C (70°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!