Castro Urdiales, Spain offers 16 beaches perfect for sunbathing, surfing, swimming, and more. Castro Urdiales is known for its Gothic-style Santa Maria de la Asuncion Church and the medieval Castle of Santa Ana. The best time to travel to Castro Urdiales, Spain, is from June to September, when the average air temperature is around 20-25°C (68-77°F) and the water temperature is 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!