East Islip, United States offers 1 beach perfect for sunbathing, surfing, swimming, and more. East Islip is known for its proximity to the scenic Great South Bay and Heckscher State Park. The best time to travel to East Islip, United States, is during late spring to early fall (May to September) when the average air temperature ranges from 60°F to 80°F and the water temperature is around 60°F to 75°F. Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!