Senamionsen, Japan offers 1 beach perfect for sunbathing, surfing, swimming, and more. Senamionsen is known for its hot springs and the Senami Onsen Resort. The best time to travel to Senamionsen, Japan, is from late spring to early autumn (May to September), with average air temperatures ranging from 15°C to 25°C and water temperatures around 20°C to 24°C. Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!