Kassari, Estonia offers 1 beach perfect for sunbathing, surfing, swimming, and more. Kassari, Hiiu, Estonia, is known for Kassari Chapel and the Kassari Landscape Reserve. The best time to travel to Kassari, Estonia, is during the summer months of June to August, when the average air temperature is around 17°C (63°F) and the water temperature is approximately 18°C (64°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!