Sea of Japan Water Temperature Today & Regional Overview

Current Water Temperature

The water temperature in the Sea of Japan today ranges from -1.3°C (Okhotsk, Russia) to 16.3°C (Fukuoka, Japan).

As of today, the minimum water temperature in the Sea of Japan ranges less than 41°F (5°C). Such water is extremely cold and not recommended for swimming without proper preparation. In these conditions, the risk of hypothermia is very high, and prolonged exposure to the water can be hazardous to your health. If you decide to swim, it is important to have the appropriate gear, such as a wetsuit. Typically, only experienced swimmers or those who practice winter swimming venture into such waters.

It is important to note that these swimming tips and recommendations apply only in good weather. When the air temperature is below 68°F (20°C), and sometimes even below 77°F (25°C), swimming can be unpleasant even with relatively high water temperatures.

Water Temperature and Swimming Conditions Throughout the Year

Month	Min	Max
January	-4°C	17°C
February	-3°C	16°C
March	-3°C	16°C
April	-3°C	18°C
May	-3°C	21°C
June	-2°C	25°C
July	0°C	29°C
August	8°C	31°C
September	6°C	30°C
October	0°C	27°C
November	-2°C	24°C
December	-3°C	20°C

The Sea of Japan exhibits marked seasonal and regional differences in surface water temperature. Along southern coasts and within sheltered bays, summer surface temperatures commonly range from about 22°C to 28°C, while more northerly sectors typically warm to 18°C–22°C. In autumn the surface cools to roughly 10°C–20°C as heat is lost to the atmosphere and storms increase. Spring sees a steady warming from near-winter values, with typical surface temperatures around 6°C–17°C depending on latitude and local currents. Winter surface temperatures fall substantially, particularly in northern and exposed areas, where values can be close to 0°C–8°C; southern sheltered waters tend to remain milder but still generally under 10°C. Offshore and deeper layers remain colder year-round, so measurements near shore will usually be warmer than those taken farther out.

Swimming Conditions

Swimming in the Sea of Japan is commonplace and seasonally permitted in most coastal recreational areas, especially during late spring to early autumn when surface temperatures are comfortable. Bathing beaches and resorts on the Japanese and Korean coasts open for visitors when water temperatures reach the mid to high teens and above. However, suitability for swimming depends on specific location, weather, currents and water quality; strong winds, rip currents, cold upwellings and occasional marine hazards can make conditions unsafe even when temperatures are moderate. Winter swimming is uncommon except for organized cold-water events and experienced enthusiasts because low temperatures and rough seas increase risk. Local advisories and lifeguard guidance should be followed for safe swimming.

Popular Resorts with the Warmest Water Today