Sea temperature in South Korea
Live water temperatures and swimming conditions across 15 beaches on the South Korea coast.
Best time to swim in South Korea
The sea in South Korea peaks in July, when the water averages around 24°C.
The main swimming season runs from June – September, when surface temperatures stay comfortable for extended sessions.
On average, 4 months a year sit above 20°C — the threshold most swimmers describe as pleasant without a wetsuit.
Shoulder months like May and October are noticeably cooler but often quieter, with fewer crowds and steadier weather.
Outside peak season the water drops toward 14°C, so a 3/2mm shorty or full wetsuit makes long swims much more comfortable.
The coldest month is typically February at around 12°C, when cold-water swimmers dominate the coast.
South Korea sea temperature history
Long-term climatology for South Korea shows an annual mean sea temperature of 18°C, ranging from 12°C in winter to 24°C at the summer peak.
The seasonal swing is roughly 12°C between the coldest and warmest month — a useful yardstick when comparing years or checking whether the current sea is running above or below average.
Recent decades have trended slightly warmer at South Korea, in line with regional sea-surface temperature records for the wider basin.
Monthly averages below are drawn from multi-decadal climatology and are updated as new observations arrive.
Values are area averages; individual beaches vary by exposure and depth.
South Korea sea temperature: frequently asked questions
What is the warmest month to swim in South Korea?
July is the warmest month in South Korea, when the sea averages about 24°C. Late-season warmth often persists a few weeks after peak.
When is the sea coldest in South Korea?
The coldest month in South Korea is typically February, when the water averages around 12°C. Cold-water swimmers and surfers dominate this period.
When can you swim in South Korea without a wetsuit?
The main swimming season in South Korea runs from June – September — about 4 months a year when the sea sits above 20°C, the level most swimmers describe as pleasant without a wetsuit.
Do I need a wetsuit in South Korea?
Outside peak summer the water in South Korea drops toward 14°C, so a 3/2mm shorty or full wetsuit makes long swims much more comfortable. In peak months most swimmers go without.
What is the average sea temperature in South Korea?
The long-term annual mean sea temperature in South Korea is about 18°C, based on multi-decadal climatology of the surrounding waters.
How do I check the current sea temperature in South Korea?
The live reading at the top of this page shows the current sea temperature in South Korea, updated hourly from marine buoy and satellite data. The 7-day forecast covers water, air, waves, wind and UV for the week ahead.
South Korea sea temperature by month
Average sea temperatures around South Korea for every month of the year, based on long-term Open-Meteo marine climatology.
| Month | Average sea | Swimming comfort |
|---|---|---|
| January | 13.0°C | Too cold for most |
| February | 12.0°C | Too cold for most |
| March | 13.0°C | Too cold for most |
| April | 15.0°C | Bracing — wetsuit advised |
| May | 18.0°C | Swimmable, refreshing |
| June | 21.0°C | Pleasant swimming |
| July ⭐ | 24.0°C | Warm swimming |
| August | 24.0°C | Warm swimming |
| September | 22.0°C | Pleasant swimming |
| October | 19.0°C | Swimmable, refreshing |
| November | 16.0°C | Bracing — wetsuit advised |
| December | 14.0°C | Bracing — wetsuit advised |
Monthly figures are modelled climatology averages, not live readings. How accurate is our data?
Warmest beaches in South Korea right now
| Beach | Region | Sea | Swim score |
|---|---|---|---|
| Hamdeok Beach | Jeju | 27.7°C | Excellent |
| Jungmun Beach | Jeju | 26.9°C | Excellent |
| Hyeopjae Beach | Jeju | 26.6°C | Excellent |
| Iho Tewoo Beach | Jeju | 26.6°C | Excellent |
| Gimnyeong Beach | Jeju | 26.5°C | Excellent |
| Naksan Beach | Gangwon | 22.4°C | Excellent |
| Haeundae Beach | Busan | 22.3°C | Excellent |
| Gwangalli Beach | Busan | 22.1°C | Excellent |
| Songdo Beach Busan | Busan | 22.1°C | Excellent |
| Songjeong Beach | Busan | 21.8°C | Excellent |
| Eurwangni Beach | Incheon | 21.6°C | Excellent |
| Dadaepo Beach | Busan | 21.5°C | Excellent |
| Sokcho Beach | Gangwon | 21.5°C | Excellent |
| Gyeongpo Beach | Gangwon | 21.4°C | Excellent |
| Mangsang Beach | Gangwon | 21.4°C | Excellent |
Sea temperature in South Korea — FAQ
How warm is the sea in South Korea in September?
The sea off South Korea averages about 22.0°C in September, based on long-term monthly averages for this coast.
When is the best time to swim in South Korea?
South Korea is warmest in July (around 24.0°C) and coldest in February (around 12.0°C). There are typically 3 months a year when the water sits above 22°C.
What is the average yearly sea temperature in South Korea?
Across all twelve months, the sea in South Korea averages about 17.6°C.
Do you need a wetsuit to swim in South Korea?
In peak season (around July, ~24.0°C) most swimmers are comfortable without a wetsuit. Outside summer, when the water drops toward 12.0°C, a 3/2mm to 5/4mm wetsuit is recommended.
Which beach in South Korea has the warmest sea right now?
Hyeopjae Beach typically has the warmest sea in September, while Haeundae Beach is the coolest of the featured beaches. Live readings for every beach are listed on this page.