Onetahi, French Polynesia offers 2 beaches perfect for sunbathing, surfing, swimming, and more. Le Portel is known for its beautiful beaches and the Fort de l'Heurt. The best time to travel to Onetahi, French Polynesia, is from May to October, when the average air temperature is around 77°F (25°C) and the water temperature is approximately 79°F (26°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!