Deerfield, United States offers 3 beaches perfect for sunbathing, surfing, swimming, and more. Deerfield, New Hampshire, United States, is known for the Deerfield Fair, one of New England's oldest and largest agricultural fairs. The best time to travel to Deerfield, United States, is in late spring (May to early June) when the average air temperature is around 70°F (21°C) and the water temperature is approximately 60°F (16°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!