Ilha de Sao Joao, Brazil offers 1 beach perfect for sunbathing, surfing, swimming, and more. Ilha de Sao Joao, Rio de Janeiro, Brazil, is known for its vibrant cultural festivals and scenic views of Guanabara Bay. The best time to travel to Ilha de Sao Joao, Brazil, is from May to September, with average air temperatures around 75°F (24°C) and water temperatures near 72°F (22°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!