The Shore calendar runs from Memorial Day (late May) through Labour Day (early September), and Toms River is no exception. Summer is when everything opens, the beaches fill, and the boardwalks come alive. It is also when the traffic on Route 37 becomes genuinely awful on Friday evenings and Sunday afternoons. If you're coming mainly for Island Beach State Park or the natural side of Barnegat Bay, late June and early September are the best compromises — warm enough to swim, crowds beginning to thin.
The shoulder seasons — May and October — have their own appeal. The weather can be excellent, the prices drop sharply, and the town itself is noticeably more relaxed. October on the Jersey Shore has a particular quality: warm afternoons, crisp evenings, and the smell of the bay in the air without the summer crush. Most restaurants and attractions remain open into October; Island Beach State Park is open year-round for hiking and birding even when swimming is no longer possible.
Winter is quiet to the point of emptiness on the barrier island, but Toms River proper functions year-round as a town of 90,000 people. Late summer is also monarch butterfly season at Island Beach, when thousands of butterflies stage there on their annual migration south — one of the better reasons to visit in September rather than July.
Hurricane season runs from June through November. The town was extensively damaged by Hurricane Sandy in October 2012, and some of the reconstruction scars are still visible. Storm systems tracking up the coast occasionally affect the area in autumn; check forecasts if you're planning a trip in that window.