May and June are the best months to visit. The weather is warm but not punishing, the beaches are uncrowded, and the restaurants and shops are fully open without the summer pressure on ferry space and accommodation. Wildflowers are up along the roadsides and the birding is excellent as shorebirds move through.
July and August bring the full summer season: crowded ferries, busy beaches, and the island's highest prices. It is still enjoyable, but you need to plan ahead — book the Cedar Island or Swan Quarter ferry well in advance and expect to share the beach. The heat and humidity in August can be heavy.
September and October rival May and June. The crowds thin out after Labor Day, the water is still warm enough to swim, and the light in October is extraordinary. Autumn birding is excellent, with raptors moving south along the barrier islands.
Winter is quiet to the point of emptiness. Most restaurants close or cut back sharply to weekends only. The ferry from Hatteras still runs, but crossings are more irregular and weather can shut things down for days. A few year-round residents keep things ticking, but the island in January is a very different place from the island in July.
Hurricane season runs June through November, with the peak in September. Ocracoke is low-lying and has flooded seriously in past storms. Check the forecast before traveling in this window.