September is the month Korea transitions from summer to autumn. The heat breaks, Chuseok brings the country’s most important holiday, the first autumn colours appear in the mountains, and the crowds from summer thin out before the November peak returns. Here is what to expect.
Quick answer: September in Korea offers comfortable temperatures (18 to 26 degrees), the Chuseok harvest festival (September 25 to 27 in 2025, check 2026 dates), early autumn foliage at Seoraksan by late September, Seoul’s palaces with thinner crowds, and Busan’s beaches in their post-summer quiet. The week around Chuseok sees major domestic travel book transport and accommodation well ahead if your trip overlaps.
Korea Weather in September
September marks a clear shift from summer. Early September still carries warmth, with temperatures of 24 to 28 degrees Celsius, but humidity drops significantly compared to July and August. By mid-September,r temperatures are settling to 20 to 24 degrees during the day with cooler evenings of 14 to 18 degrees. The sky clears distinctly Korean autumn light has a particular brightness and clarity that makes outdoor photography excellent. Rain is possible but less frequent than the summer monsoon period.
Late September can feel like early autumn, particularly in the evenings. A light jacket becomes useful by the end of the month, especially in mountainous areas like Seoraksan.
Chuseok: Korea’s Harvest Festival
Chuseok (추석) is Korea’s most important holiday, a three-day celebration of the harvest and ancestral gratitude sometimes compared to Thanksgiving. The date follows the lunar calendar and falls on the 15th day of the 8th lunar month in 20, which is mid-September (verify the exact date closer to travel, as lunar calendar dates shift yearly).
What Chuseok means for travellers:
- Transport: The KTX and intercity buses are booked solid in both directions for the full holiday window. Tickets sell out weeks ahead. Book or avoid travelling on the core Chuseok days.
- Shops and restaurants: Many smaller restaurants and local shops, as well as some attractions, close for the holiday. Convenience stores remain open. Major tourist sites in Seoul stay open but may have adjusted hours.
- Atmosphere: Seoul empties as residents return to their hometowns. The city has a rare quietness during the holiday season. If you are already in Seoul, this is actually a pleasant time to visit major sights without the usual crowds.
- Gyeongbokgung night tour: The Gyeongbokgung Palace Night Tour (야간개장) typically operates around Chuseok and is one of the most atmospheric experiences in Seoul, with the illuminated palace buildings at night, and far fewer visitors than during the day.
Seoraksan National Park: Korea’s First Autumn Colour
Seoraksan (설악산) in Gangwon Province is where the Korean autumn begins. The high granite peaks at 1,708 metres see the first colour changes in late September, typically 3 to 4 weeks before the foliage peaks in Seoul and southern Korea. The combination of dramatic rocky peaks, deep forested valleys, and the early red and orange maple colour makes late September one of the finest times to visit.
Getting there: Intercity bus from Seoul’s Express Bus Terminal (동서울터미널) or Dong Seoul Bus Terminal to Sokcho city (about 2.5 hours, 17,000 to 22,000 won). Sokcho is the gateway town for Seoraksan. The main park entrance (Soraksan area, 5,000 won entry) is accessible by city bus from Sokcho.
The Biseondae rock and the Ulsanbawi hiking circuit (about 4 to 5 hours return, involving chain-assisted steep sections) give the fullest sense of the landscape. The Heundeulbawi (a large balancing rock located a short distance from the entrance) is the classic introductory hike. September weekdays are far quieter than October weekends.
Seoul in September
Seoul in September has the pleasant character of summer winding down without the full autumn tourist surge that arrives in October. The palaces Gyeongbokgung, Changdeokgung, and Deoksugung are comfortable to walk in the September temperatures. The Secret Garden at Changdeokgung (guided tour required, 12,000 won, booking recommended) shows early signs of the autumn colour change in the garden’s forested sections by late September.
The Han River parks are excellent in September. The summer water activities (paddleboarding, kayaking) are still available through most of the month, and the evening riverbank culture persists with the more bearable temperatures. Yeouido Hangang Park and Ttukseom Hangang Park are both good destinations for September evenings.
Busan in September
September is a transition month at the beach. Haeundae Beach officially ends its summer season around mid-September, but the water is still warm, and the beach becomes genuinely peaceful. Early September beach walks at Haeundae before 9 am, with the crowds gone and the East Sea at its clearest, are among Busan’s finest experiences. In September, the Gamcheon Culture Village and Haedong Yonggungsa Temple have considerably shorter queues than during the summer peak.
Preparation for the Busan International Film Festival (BIFF) begins in September with pre-festival events and the release of the full programme, though the main festival runs in early October. Accommodation around Haeundae books up for October if you’re planning to attend BIFF. Book your September-to-October Busan accommodation together.
Korean Food in September
Chuseok foods: The holiday has specific foods associated with it. Songpyeon (송편) are half-moon-shaped rice cakes filled with sesame seeds, sweet bean paste, or chestnuts, steamed over pine needles, the definitive Chuseok food, widely sold at markets and convenience stores in the weeks before the holiday. Japchae (glass noodles with vegetables and meat), galbi jjim (braised short ribs), and various seasonal vegetable dishes also feature in the traditional Chuseok table.
Autumn seafood begins: September marks the start of the autumn crab season in Korea. Daege (snow crab) and kkotge (blue crab) at Jagalchi Market in Busan and the Noryangjin Fisheries Market in Seoul are at their seasonal best from September through November. Hairy crab (털게, teoege) is a Korean delicacy, specifically in autumn.
Practical Notes for September in Korea
Chuseok transport: Book KTX and intercity bus tickets as soon as they go on sale (typically 1 month in advance). If you cannot get tickets for Chuseok travel days, adjust your travel plan by one day in either direction.
What to wear: Light clothing for early September, transitioning to light layers by mid-month. A jacket for evenings from mid-September. Hiking at Seoraksan requires proper footwear and warm layers, given the elevation.
Accommodation: September is easier than October for booking in most Korean destinations. The week around Chuseok is an exception, so book early.
