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Warmer September weather to delay fall foliage by up to a week: Forecasters

Published: 11 Sep. 2025, 17:36 Updated: 11 Sep. 2025, 17:50

Visitors walk under autumn foliage in Inje, Gangwon, in Nov. 2, 2024. [YONHAP]

The fiery colors of Korea’s fall will arrive later than usual this year. Unseasonably warm September weather is expected to delay the first signs of autumn foliage by up to a week, forecasters say.

Private weather service K Weather predicted that temperatures in mid to late September will remain higher than average, driven by migratory high-pressure systems. On Mount Seorak, the first trees are expected to turn red and yellow around Oct. 2 — four days later than normal. The benchmark for “first foliage” is when about 20 percent of trees at the summit have changed color.

From there, the colors will move south at a pace of 20 to 25 kilometers per day. Central regions should see their first foliage between Oct. 2 and Oct. 22. In the south, it is forecast to arrive between Oct. 18 and 26. Seoul’s Mount Bukhan is projected to show its first foliage on Oct. 22, seven days later than the seasonal average.

The peak foliage, which typically occurs about two weeks after the first foliage, is expected between Oct. 18 and Nov. 1 in central Korea and from Oct. 28 to Nov. 7 in the southern part of the country.

Mount Kumgang's autumn foliage, tinged red, as captured by drone footage aired by North Korea’s Korea Central Television on Oct. 24, 2023. [YONHAP]

Later colors, warmer climate

Deciduous trees begin to change color when the daily low temperature drops below 5 degrees Celsius (41 degrees Fahrenheit). The timing of autumn foliage is influenced by early September temperatures, with cooler weather generally bringing earlier color changes.

Due to global warming, the onset of autumn foliage has been gradually delayed. According to K Weather, compared to the 1990s, the first foliage has been delayed by 12 days on Mount Jiri and by eight days on Mount Odae and Mount Naejang in the past five years. Peak foliage has also shifted later, by eight days on Mount Jiri and seven days on Mount Worak and Mount Palgong.

“Between 2020 and 2024, average nationwide temperatures in September and October rose by 1.7 degrees and 0.8 degrees Celsius, respectively, compared to the 1990s,” K Weather said. “As autumn temperatures continue to rise, both the first appearance and peak of fall foliage are now occurring later across most of the country.”

This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
BY CHON KWON-PIL [[email protected]]