Summer (Memorial Day to Labour Day) is high season at the Jersey Shore — beaches packed, boardwalks lit, hotels at peak prices. Inland it's often hot and humid, with thunderstorms common in the afternoons.
September and October are arguably the best months to visit: warm enough to swim through mid-September, the shore towns quieter and cheaper, and the inland forests and Pine Barrens turning colour through October. The Delaware Water Gap and the northwest hills are at their best.
Winter is cold and grey, with occasional heavy snow. The shore largely shuts down. Spring (April–May) is mild and pleasant, with apple and cherry blossom in the Garden State sense.