Fall foliage forecast to arrive earlier than last year as cooler weather leaves summer behind

Cooler weather is settling in across Korea, bringing fall foliage with it — and the rich autumn colors are expected to arrive earlier than last year.

The first fall foliage of the year is expected at Mount Seorak in Gangwon on Sept. 30, according to private weather forecaster Kweather.

That would be two days earlier than last year, when the first foliage was observed on Oct. 2. However, this year's start is still two days later than the average date of Sept. 28. The start of fall foliage is defined as the point when 20 percent of a mountain has changed color from the summit downward.

The fall foliage front is then expected to move southward at a rate of around 20 to 25 kilometers (12 to 16 miles) per day.

For central Korea, first foliage is expected between Sept. 30 and Oct. 18. Southern Korea is expected to see its first foliage between Oct. 19 and 27.

Mount Naejang, a popular fall foliage destination straddling North and South Jeolla, is expected to see its first foliage on Oct. 27. This year's start is 11 days earlier than last year.

The timing of the first fall foliage depends on temperature changes from early September onward, with cooler temperatures generally bringing an earlier start.

“Temperatures in mid-September are expected to remain around average levels, while those in late September are forecast to be somewhat higher than average as the country comes mainly under the influence of high pressure,” said Lee Jae-jeong, head of Kweather's forecasting team. “Last year, the late summer heat persisted for a long time, so we expect the foliage to arrive a little earlier this year than last year.”

Fall foliage typically reaches its peak about two weeks after the first leaves begin changing color. Peak foliage is also expected to arrive earlier than last year, although later than average.

Peak foliage is forecast to begin at Mount Seorak on Oct. 19. Central Korea will reach its peak between Oct. 19 and Nov. 1, and southern Korea's will be between Nov. 1 and 11. Peak foliage is defined as the point when 80 percent of a mountain has changed color from the summit downward.

Deciduous trees begin changing color when daily minimum temperatures fall below 5 degrees Celsius (41 degrees Fahrenheit). Fall colors tend to be more vivid in mountainous areas than on flat terrain, in areas with less rainfall than in wetter areas and in sunny locations that receive more sunlight.

The onset and peak of fall foliage have gradually been occurring later as autumn temperatures rise due to global warming. Nationwide average temperatures in September and October from 2021 to 2025 were 2.3 degrees Celsius and 1.4 degrees Celsius higher, respectively, than from 1991 to 2000. The first foliage and peak foliage have consequently been delayed by around a week compared with the past.

The first foliage at major mountains nationwide arrived an average of 7.3 days later from 2021 to 2025 than from 1991 to 2000, according to an analysis by Kweather. Peak foliage arrived 6.6 days later during the same period.

At Mount Bukhan, the first foliage arrived seven days later, while Mount Naejang and Mount Jiri saw delays of 12 and 14 days, respectively. Peak foliage arrived 11 days later at Mount Jiri and 10 days later at Mount Wolak and Mount Palgong.

BY CHON KWON-PIL [[email protected]]