Jeju weather in September
Temperature, sea and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Good
Best time to visit: April – June, September – October
What is the weather like in Jeju in September?
In September, Jeju is warm: daytime highs average 25 °C, and even at night it stays warm at around 22 °C. The sea averages 25.1 °C – pleasant for swimming. Expect around 5 hours of sunshine a day. Rain is frequent, with about 14 rainy days and 200 mm in total. The air is often humid and muggy. All in all, September is a good month for a holiday in Jeju.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 52 | 67 | 82 |
| Day | 29° | 25° | 21° |
| Night | 26° | 22° | 17° |
| Sea | 27° | 25° | 22° |
| Sun | 6 h | 5 h | 6 h |
| Rain days | 17 | 14 | 7 |
More details for September
- Daylight
- 12 h 26 min06:16 – 18:42
- UV index
- 8 · very highclear sky, noon (estimate)All months
- Muggy days
- 20 daysdew point 18 °C or moreAll months
- Wind
- 17 km/haverage daily peakAll months
- Cloud cover
- 60 %on averageAll months
- Hot days
- 1 day30 °C or moreAll months
- Snow days
- 0 days1 cm or more of fresh snow
- Time zone
- UTC+9Asia/Seoul
How the score comes together
- Temperatureweight 50 %100 %
- Sunshineweight 20 %38 %
- Few rainy daysweight 30 %31 %
Each factor is rated from 0 to 100 % and weighted for the travel style “City break”.
What to pack in September
- Swimwear
- Sunscreen
- Sunglasses & sun hat
- Light, breathable clothes
- Insect repellent
- Rain jacket or umbrella
Jeju in September: quick answers
Is Jeju hot in September?
Warm rather than hot: in September, daytime highs in Jeju average 25 °C and nights cool to about 22 °C.
Can you swim in Jeju in September?
Yes. In September the sea averages 25.1 °C – pleasant for swimming.
Does it rain much in Jeju in September?
Rain is frequent, with about 14 rainy days and 200 mm in total.
Jeju month by month
The whole year in JejuAll destinations: South KoreaWhere to go in SeptemberSea temperature in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences