What to Actually Pack for Korea in October
October in Korea moves through two seasons inside a single day. Walk a Seoul street at one in the afternoon and a short-sleeved shirt feels warm on your back; stand in the same spot at nine at night and the back of your neck goes cold. When 28 overseas YouTubers who visited Korea in September 2026 were asked what went wrong, this was the second most common answer after payment trouble. Fifteen of the 28 said they had misread the weather and packed the wrong clothes. That is what happens when travel advice compresses a Korean autumn into a single word: mild.
At a glance: October normals (Korea Meteorological Administration, 1991–2020 climate normals) · Seoul morning low 10.6°C / daytime high 20.2°C · Busan 14.5°C / 22.5°C · Jeju 15.7°C / 21.6°C · tourist hotline 1330
The 1991–2020 climate normals published by the Korea Meteorological Administration put Seoul's October monthly mean at 15.0°C, but inside that month the morning low sits at 10.6°C and the daytime high at 20.2°C. The temperature swings 9.6 degrees within a single day. Busan runs from 14.5°C to 22.5°C, a swing of 8.0 degrees, and Jeju from 15.7°C to 21.6°C, a swing of 5.9. The farther south you go, the warmer the afternoons and the milder the mornings. Seoul and Jeju differ by more than five degrees in the morning alone, so an itinerary covering both cities needs a bag that covers both. The answer is therefore not one thick garment but several thin layers. Pack a short-sleeved or light long-sleeved top, a thin knit or hoodie to go over it, and a light jacket that blocks wind. Those three layers carry you through both the morning and the afternoon of a Korean October. What to leave behind is just as clear: sandals, sleeveless tops, and a heavy midwinter coat. With afternoon highs in the low twenties, a winter coat takes three kilograms out of your bag and never comes out of it.
You should also adjust the assumption that indoors will always be warmer than outdoors. Korean government offices and public museums and libraries are required, under the national regulation on rational energy use by public institutions, to keep the average indoor temperature at or below 18°C when the heating is running. Take your jacket off in one of those buildings and you may feel colder inside than out. The reverse happens on the subway, on buses and in shops, where air conditioning often lingers into mid-October and the ride is the chilliest part of the day. Accommodation usually runs on ondol, the Korean system that heats the entire floor, so your feet stay warm while the air turns dry. Arrive unprepared and you will buy clothes here, and that costs money. At Uniqlo Korea's official prices, a light padded jacket is 89,900 won and a thin thermal undershirt is 16,900 won. One outer layer and one thermal top for a single person comes to 106,800 won; for two people it passes 210,000 won. On top of that, the three kilograms of summer clothing you carried in for nothing still has to be carried home.
Cross into November and the same clothes stop working. In the same set of normals, Seoul's monthly mean drops from 15.0°C in October to 7.5°C in November, and the morning low falls from 10.6°C to 3.5°C. Busan goes from 17.9°C to 11.9°C, and Jeju from 18.6°C to 13.3°C. If your trip leaves in late October and runs into early November, a light jacket alone will not be enough. Add a thermal layer to wear underneath and one scarf that covers the neck. Same country, same cities, and yet the wardrobe skips a whole season in the space of two weeks.