Lagoa do Siri, Brazil offers 1 beach perfect for sunbathing, surfing, swimming, and more. Lagoa do Siri is known for its beautiful lagoon and tranquil beach setting. The best time to travel to Lagoa do Siri, Brazil, is from April to September, with average air temperatures around 75°F (24°C) and water temperatures near 77°F (25°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!