Ulleungdo in September

Ulleungdo's weather swings between extremes, and timing your visit wrong means missing half the island's appeal. May through October offers the most reliable ferry service and hiking conditions. July and August bring crowds and premium prices, but also the warmest water temperatures and longest days. Book accommodation months ahead for summer visits — the island only has about 500 beds total. September hits the sweet spot: fewer crowds, stable weather, and autumn colors starting to paint the mountainsides. Ferry schedules remain frequent, and you'll actually find restaurant tables without waiting. Water temperatures stay comfortable for diving through early October. Late spring (May-June) works well for serious hikers. The weather stays cool enough for long treks, wildflowers bloom across the interior, and accommodation costs drop significantly. But pack layers — mountain weather changes fast. Avoid winter unless you enjoy gambling with ferry schedules. Services run sporadically, many restaurants close, and hiking trails become treacherous. That said, if you do make it over during a clear winter day, the snow-capped volcanic peaks and empty landscapes offer a completely different perspective on the island. Weather apps lie about Ulleungdo conditions. Check the ferry company's website for real-time updates, and always have backup plans for both arrival and departure.