Jeju Island Water Temperature
Updated Thu 12:18 (Asia/Seoul)
South Korea · Forecast updated Sep 24, 2026, 12:18 UTC
Current Sea Temperature
26.9°C
80.4°F
Warm water
Valid Sep 24, 2026, 12:18 (Asia/Seoul). Source: stored Open-Meteo marine forecast. Temperature is not a safety rating or snorkel score.
Versus this month's average
2.3°C below
The typical September average is 29.2°C (84.6°F) from the historical baseline.
Recent trend
Cooling by 0.5°C
Seven-day average: 26.9°C, versus 27.3°C in the prior seven days.
What to wear
Warm water
Most people are comfortable in swimwear or a light rash guard.
Cold tolerance varies. Wind, session length, sunshine, and exertion also affect comfort; temperature alone does not describe sea conditions or replace the snorkel forecast.
Typical Sea Temperature Over the Year
In the historical baseline for Jeju Island, typical monthly averages range from about 15.5°C (59.9°F) in March to 30.0°C (86.0°F) in August.
Over the past 30 days, the average sea temperature in Jeju Island has been 28.1°C.
Historical baseline (full year)
Northern Hemisphere. Summer is generally June–August; winter is December–February.
Typical monthly sea-surface temperature near Jeju Island, calculated from hourly observations for 2023–2025. This is not this site's forecast archive.
| Month | Typical range | Average |
|---|---|---|
| January | 16.2–17.1°C | 16.7°C / 62.1°F |
| February | 15.7–16.2°C | 16.0°C / 60.8°F |
| March | 14.1–16.4°C | 15.5°C / 59.9°F |
| April | 15.0–17.4°C | 16.4°C / 61.5°F |
| May | 17.0–18.8°C | 18.2°C / 64.8°F |
| June | 21.7–22.4°C | 22.1°C / 71.8°F |
| July | 26.1–27.9°C | 26.7°C / 80.1°F |
| August | 29.5–30.9°C | 30.0°C / 86.0°F |
| September | 28.1–29.9°C | 29.2°C / 84.6°F |
| October | 24.7–27.6°C | 26.1°C / 79.0°F |
| November | 22.2–23.1°C | 22.8°C / 73.0°F |
| December | 19.2–19.5°C | 19.3°C / 66.7°F |
Source: Open-Meteo Marine API, MeteoFrance sea-surface temperature dataset. Nearest sea grid cell (33.21, 126.54). Each month is the mean of yearly monthly means; the range is the lowest and highest of those yearly monthly means. Open-Meteo methodology.
Water temperature by month
Each month uses the 2023–2025 baseline. The range is the lowest and highest yearly monthly mean, not an hourly extreme.
Jeju Island in January
Typical January water temperature near Jeju Island is 16.7°C (62.1°F), with yearly monthly means from 16.2–17.1°C.
Jeju Island in February
Typical February water temperature near Jeju Island is 16.0°C (60.8°F), with yearly monthly means from 15.7–16.2°C.
Jeju Island in March
Typical March water temperature near Jeju Island is 15.5°C (59.9°F), with yearly monthly means from 14.1–16.4°C.
Jeju Island in April
Typical April water temperature near Jeju Island is 16.4°C (61.5°F), with yearly monthly means from 15.0–17.4°C.
Jeju Island in May
Typical May water temperature near Jeju Island is 18.2°C (64.8°F), with yearly monthly means from 17.0–18.8°C.
Jeju Island in June
Typical June water temperature near Jeju Island is 22.1°C (71.8°F), with yearly monthly means from 21.7–22.4°C.
Jeju Island in July
Typical July water temperature near Jeju Island is 26.7°C (80.1°F), with yearly monthly means from 26.1–27.9°C.
Jeju Island in August
Typical August water temperature near Jeju Island is 30.0°C (86.0°F), with yearly monthly means from 29.5–30.9°C.
Jeju Island in September
Typical September water temperature near Jeju Island is 29.2°C (84.6°F), with yearly monthly means from 28.1–29.9°C.
Jeju Island in October
Typical October water temperature near Jeju Island is 26.1°C (79.0°F), with yearly monthly means from 24.7–27.6°C.
Jeju Island in November
Typical November water temperature near Jeju Island is 22.8°C (73.0°F), with yearly monthly means from 22.2–23.1°C.
Jeju Island in December
Typical December water temperature near Jeju Island is 19.3°C (66.7°F), with yearly monthly means from 19.2–19.5°C.
Forecast archive (growing)
These values come from hourly forecasts SnorkelForecast has stored. They cover only months with records and do not replace the historical baseline.
| Month | Min | Average | Max |
|---|---|---|---|
| June | 22.2°C / 72.0°F | 23.0°C / 73.4°F | 24.6°C / 76.3°F |
| July | 23.4°C / 74.1°F | 26.7°C / 80.0°F | 30.9°C / 87.6°F |
| August | 27.8°C / 82.0°F | 28.9°C / 84.1°F | 30.5°C / 86.9°F |
| September | 26.5°C / 79.7°F | 27.7°C / 81.8°F | 29.8°C / 85.6°F |
Partial coverage: 4 calendar months with records. Profile calculated from 2781 hourly forecast records across 4 monthly periods. This is a growing archive, not a long-term climate normal.
About the water at Jeju Island
Volcanic island with clear coves, lava arches and the famous haenyeo divers.
- Area
- Jeju
Jeju Island Water Temperature: Common Questions
What is the water temperature in Jeju Island today?
The current sea surface temperature near Jeju Island is 26.9°C (80.4°F). Over the last 30 days, the average has been 28.1°C.
When is the water warmest in Jeju Island?
The water is typically warmest in August, at around 30.0°C (86.0°F) in the 2023–2025 historical baseline.
When is the water coldest in Jeju Island?
The water is typically coldest in March, at around 15.5°C (59.9°F) in the same historical baseline. A wetsuit is usually recommended during this period.
Can you swim in Jeju Island today?
At 26.9°C, the water is usually comfortable for swimming and snorkeling.
Full Snorkeling Forecast
See how today's sea temperature, wave height, wind, and tides combine into a detailed snorkeling score for Jeju Island.
View Snorkel Forecast →