Johnston City, United States offers 1 beach perfect for sunbathing, surfing, swimming, and more. Johnston City is not particularly known for travel and beach tourism. The best time to travel to Johnston City, United States, is in late spring (May), when the average air temperature is around 70°F (21°C) and water temperature is approximately 65°F (18°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!