When's the best time to visit Seoul in 2026?

Seoul is easiest in October. Daytime highs run near 20°C (68°F), October rain usually totals about 50 mm, and on most days the air is clear enough to see the granite ridges of Bukhansan from the deck of Namsan Seoul Tower. At 2am on 17 October 2026 the city read 14.2°C under a clear sky, so plan on a light jacket over a T-shirt after dark. The maples and ginkgoes turn from the last week of October into the first week of November, and on Samcheong-dong the fallen ginkgo fruit gets crushed underfoot and gives off a sour, buttery smell that every Seoulite knows. Changdeokgung is a UNESCO World Heritage Site, and its Secret Garden is open by guided tour. Book the tour the moment the online window opens, because autumn slots tend to go within hours.

Spring comes second, with a catch. Cherry blossoms usually peak in the first ten days of April at Seokchon Lake in Songpa and along Yunjung-ro on Yeouido, and on a Saturday afternoon the crowds there barely move. The bigger problem is hwangsa, the yellow dust that blows in from the Gobi and Inner Mongolia between March and May, often on top of Seoul's own fine-dust readings. On bad days the sky over Gwanghwamun turns a flat beige and your throat feels scratchy by noon. Check the air-quality index each morning, and carry a KF94 mask, which GS25 and CU convenience stores sell for a couple of thousand won. Save indoor days, such as the National Museum of Korea in Yongsan, for the worst-air dates. Late May is clearer, warms to the mid-20s, and is quieter than either April or October.

If your dates are flexible, avoid July and August. Jangma, the monsoon, usually arrives in late June and deposits most of Seoul's roughly 1,400 mm of yearly rain by early August, with July alone capable of delivering close to 400 mm. After the rains come temperatures in the low 30s, and the walk from Anguk Station up to Bukchon feels like breathing through a damp towel. January presents the opposite problem: highs hover near freezing, lows reach minus 10°C, and the wind off the Han River stings bare ears. The upside is that Myeongdong hotel rates can drop to around 100,000 won (about US$75) a night, and the courtyards of Gyeongbokgung are close to empty. If winter is the window you have, pack thermal layers and plan indoor afternoons in Insadong teahouses, where a cup of hot yuja-cha tastes of citrus and honey.

Two holidays can reshape the city regardless of when you visit. Chuseok, the harvest holiday, falls in September or early October depending on the lunar calendar, and for about three days many family-run restaurants in Jongno and Mapo close while KTX trains out of Seoul Station sell out. Seollal, the Lunar New Year in January or February, has the same effect. Both Gyeongbokgung and Changdeokgung stay open through each of these holidays and usually waive the entry fee, making the palaces your safest plan on those dates. One more note for October: the Seoul International Fireworks Festival fills Yeouido Hangang Park on a Saturday in early October and draws around a million people to the riverbank. Book any Yeouido hotel weeks ahead, or watch from Ichon Hangang Park on the south bank opposite.