El Rosario, Nicaragua offers 9 beaches perfect for sunbathing, surfing, swimming, and more. El Rosario, Chinandega, Nicaragua, is known for its proximity to the Cosiguina Volcano and the Gulf of Fonseca. The best time to travel to El Rosario, Nicaragua, is from December to April, with average air temperatures around 85°F (29°C) and water temperatures near 82°F (28°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!