Lake Grassmere, New Zealand offers 2 beaches perfect for sunbathing, surfing, swimming, and more. Lake Grassmere is known for its large saltworks, where sea salt is harvested and processed. The best time to visit Lake Grassmere, New Zealand, is during the summer months of December to February, when the average air temperature is around 20-25°C (68-77°F) and the water temperature is approximately 18-20°C (64-68°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!