Rio San Juan, Dominican Republic offers 13 beaches perfect for sunbathing, surfing, swimming, and more. Rio San Juan is known for the Gri Gri Lagoon and Playa Caleton. The best time to travel to Rio San Juan, Dominican Republic, is from December to April, with average air temperatures around 77-86°F (25-30°C) and water temperatures about 79-82°F (26-28°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!