Autumn colour in Korea starts on the high peaks of Gangwon in late September and works south and downhill through October and November. In a normal year Seoraksan peaks around 17 October, Bukhansan on the northern edge of Seoul around 28 October, Naejangsan around 4 November and Duryunsan, near the south-western tip of the peninsula, around 10 November; the streets and palaces of central Seoul turn from late October into mid-November. The table gives, for 17 mountains roughly from north to south, what the Korea Meteorological Administration (KMA) has observed in 2026, the published forecasts, the usual peak and a festival nearby.
The dates use two yardsticks. KMA records first colour when about 20% of a mountain, from the summit down, has turned and the peak at about 80%; the private forecasters Weather i and K-Weather use the same measures. The Korea Forest Service (KFS) map counts a peak when at least half of the observed trees have turned, so its dates are not directly comparable with KMA's. KMA publishes observations only, not forecasts.
In early September both private forecasters expected a late season after the hot summer: K-Weather put first colour 2–8 days and the peak 2–9 days behind normal, and Weather i forecast Seoraksan's peak for 25 October. So far the north has come on time instead. Seoraksan's first colour came on 28 September, its normal date, and news reports on 18 October put its peak on 16 October, a day early; Odaesan peaked on 14 October, also a day early, and Bukhansan's first colour on 14 October came nine days before Weather i's forecast. September 2026 was 1.2°C warmer than normal, against 4.2°C in 2024 and 2.5°C in 2025. Further south the picture is mixed. On 16 October Palgongsan reached first colour a day before its normal date, Juwangsan on its normal date and Gyeryongsan eight days earlier than in 2025; but on 18 October Songnisan had still not turned (normal 14 October), and on 16 October Mudeungsan had not either.
As of 29 October the latest KMA figures, from 22 October, show Seoraksan and Odaesan past their peak, Chiaksan peaking on 19 October and Deogyusan on 20 October, a day before its normal date. Every other mountain in the table except Naejangsan and Duryunsan had reached first colour: Songnisan and Gayasan on 19 October, five days after Songnisan's normal date, and Mudeungsan on 21 October, its normal date. For the rest of October, look to Sobaeksan, Woraksan, Songnisan, Bukhansan (usual peak 28 October) and Jirisan; from late October into early November, to Palgongsan, Gyeryongsan, Juwangsan and Gayasan; and for the first half of November, to Naejangsan, Mudeungsan, Duryunsan, Hallasan's 1100 Road and central Seoul.
