When Korea's autumn leaves peak in 2026 — Seoraksan from 20 October

On 22 September the Korea Forest Service published its 2026 autumn foliage peak forecast: three maps, one each for maples, oaks and ginkgo, giving an expected peak date for 35 mountains and arboretums across the country. The colour starts in the northern mountains of Gangwon in early October, reaches its national peak in late October, and carries on at the southern arboretums into mid-November. The first thing to check on any date is which trees it refers to.

When do the leaves peak at Seoraksan and Naejangsan?

The press release names four mountains. The table below takes those four and looks each up on all three maps. On the maple map alone the colour moves south over 17 days, from Seoraksan to Hallasan; in the oak column, Naejangsan and Hallasan peak at about the same time as Seoraksan.

Why does the same mountain have different dates?

Maples turn red, oaks go brown and gold, ginkgo turns yellow, and they do not turn at the same speed. That is why the Forest Service publishes a separate map for each, and why a mountain's "peak" changes depending on the map. Hallasan has the widest gap of the four: 6 November for maples against 25 October for oaks, 12 days apart. Whether you are going for red maples or for whole hillsides turning brown and gold decides which map you should be reading.

Lay the three maps over each other and the earliest date anywhere is not Seoraksan but oaks at Sobaeksan and ginkgo at Geumwonsan (16 October). The latest is maples at Halla Arboretum on Jeju (19 November). "North first, then south" is a clear pattern for maples, not a rule that holds for every species and site.

Where was the first autumn colour this year?

Before the forecast, on 17 September, the Korea National Arboretum reported that the year's first colour had been seen on 14 September in the Jeombongsan forest genetic resource reserve in Gangwon. It was recorded by a volunteer in the arboretum's citizen plant-phenology programme, who noticed the change in the leaves on site and logged it with photographs. Anyone can log observations and see the first-colour records in the programme's web app (knpn.nature.go.kr, in Korean). The photographs below are early colour, not peak.

What is the forecast based on?

• Field observation — long-term plant-phenology records the Forest Service and the Korea National Arboretum have kept since 2009 with public arboretums in each region
• Mountain weather — forest weather data from the National Institute of Forest Science's mountain weather station network
• Next — wide-area forest observation from the agriculture and forestry satellite, to be added to improve accuracy

All 35 sites on the maps

Getting there, and what to know on the day

None of this needs a ticket: Korea's national parks charge no entrance fee, and you can walk into Seoraksan, Naejangsan or Jirisan without booking anything. What catches visitors out is the designated entry-time system — each trail has a latest start time and a time by which you must be descending, set by season and enforced by rangers — and the autumn fire-risk closures, which can shut a trail at a day's notice. Check the Korea National Park Service's trail-closure page on the morning you go, not the week before. Mountain shelters on Jirisan and Seoraksan are booked through reservation.knps.or.kr and go quickly at weekends in the colour season. Closer to Seoul, the Korea National Arboretum at Pocheon (forecast peak 29 October for maples, 2 November for oaks) admits cars only with a booking made up to 30 days ahead, but arriving on foot or by public transport needs no booking at all. Weekends at peak are crowded on the best-known ridges; a weekday a few days either side of the forecast date usually shows the same colour with far fewer people.