Old Grimsby, United Kingdom offers 3 beaches perfect for sunbathing, surfing, swimming, and more. Old Grimsby, England, United Kingdom, is known for its proximity to the Tresco Abbey Garden and the stunning beaches of the Isles of Scilly. The best time to travel to Old Grimsby, United Kingdom, is from June to August, with average air temperatures around 15-20°C (59-68°F) and water temperatures around 15°C (59°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!