Jeju Weather in September: What to Expect
In September, Jeju averages highs of 25.6°C and lows of 21.6°C, with about 17 rainy days (~361 mm). Verdict: Wet season — plan around rain — ~17 rainy days this month. That makes it the hottest of South Korea's 6 main cities this month.
September on Jeju brings persistent warmth, with daytime highs around 25.6°C feeling quite humid, especially given it's typically the hottest month among South Korean cities. Nights offer only slight relief at 21.6°C. Expect frequent rain, averaging 17 days, so sightseeing at coastal areas or natural wonders like Hallasan National Park and the Lava Tubes often involves navigating showers. The early mornings or late afternoons are generally the most comfortable times to be outdoors. Pack light, quick-drying clothing and a compact umbrella.
Jeju vs other South Korea cities in September
South Korea is not one climate. In September, Jeju runs to 25.6°C while Sokcho sits at 23.3°C — a 2°C spread. Here is where Jeju falls:
What to pack for Jeju in September
With highs near 25.6°C and lows around 21.6°C, pack light summer clothing plus a thin layer for evenings, a compact umbrella or rain shell.
Jeju is on the coast — add swimwear; the water can feel cool for swimming this month.
What to do in Jeju in September
With 25.6°C midday highs, start outdoor sights early and keep afternoons for shaded or indoor stops. Top sights:
Public holidays in South Korea, September
- 2026-09-24 — Chuseok
- 2026-09-25 — Chuseok
- 2026-09-26 — Chuseok
- 2027-09-14 — Chuseok
- 2027-09-15 — Chuseok
- 2027-09-16 — Chuseok
Jeju in September — FAQs
What is the weather like in Jeju in September?
In September, Jeju averages daytime highs of 25.6°C and overnight lows around 21.6°C, with roughly 17 rainy days and about 361 mm of rain across the month. Wet season — plan around rain — ~17 rainy days this month.
Is September a good time to visit Jeju?
Wet season — plan around rain. Plan outdoor sights for early morning and keep midday for indoor or shaded activities. Among South Korea's cities, Jeju is the hottest this month.
What should I pack for Jeju in September?
For September (21.6–25.6°C), pack light summer clothing plus a thin layer for evenings, a compact umbrella or rain shell.
What is there to do in Jeju in September?
Jeju's main sights include Jeju Volcanic Island and Lava Tubes, Hallasan National Park, Dadohaehaesang National Park. Time outdoor sites for early morning given the midday heat.
Are there public holidays in South Korea in September?
Yes — Chuseok (2026-09-24), Chuseok (2026-09-25), Chuseok (2026-09-26), Chuseok (2027-09-14), Chuseok (2027-09-15), Chuseok (2027-09-16). Sites can be busier or closed around these dates.
Jeju weather by month: