Posadas, Paraguay offers 3 beaches perfect for sunbathing, surfing, swimming, and more. Posadas, Misiones Province, Paraguay, is known for its proximity to the Jesuit Missions of the Guaranis, a UNESCO World Heritage Site. The best time to travel to Posadas, Paraguay, is from May to September, with average air temperatures around 18-25°C (64-77°F) and water temperatures approximately 20-22°C (68-72°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!