Overview

Since our country is very long from north to south, there are many climate zones from subarctic to subtropical. The average precipitation in Japan is said to be about 1,700 mm per year. Globally, precipitation is relatively high. This is because Japan is an island country surrounded by the sea on all sides, and the atmosphere that comes across the sea contains a large amount of water vapor that evaporates from the sea surface.

In summer, clouds coming from the Pacific bring rain. From July to October, typhoons come from the south and cause damage. On the other hand, in winter, clouds coming from the Sea of Japan bring snow and rain. The flatlands and mountains along the Sea of Japan get a lot of snow, especially in the northern areas from Hokkaido to the Tohoku and Chubu regions.

At the turn of the season, the weather becomes unstable. March has relatively more rainy days and can be windy. From June to mid-July, except for some areas such as Hokkaido, the rainy season called “Tsuyu” begins. September also has relatively many rainy days. During these interseasonal periods, the weather can be unpredictable and not ideal for travel. Conversely, since it is the off-season, flight and hotel fares are relatively cheap.

The best seasons for tourists are spring from late March to May and autumn from October to November. In fact, tourist spots all over the country are bustling with tourists during these times.

If you go to Japan in summer, please pay attention to typhoon information. Especially from July to September, trains and planes may be canceled due to typhoons. Make sure to check the weather forecast.

Recently, due to abnormal weather, the damage caused by heavy rain is increasing. Especially from June to July, heavy rains can occur in western Japan, mainly in Kyushu.

Japan’s Climate Divisions

In winter, the Japanese archipelago has widely different climates in different regions.

1: Climate of Hokkaido

1-1: Hokkaido (Sea of Japan side)

The climate of the Sea of Japan side of Hokkaido is characterized by its heavy snowfall in winter, with an average temperature of -3 degrees Celsius. In summer, the temperature rises to around 20 degrees Celsius, with frequent rainfall. The region is known for its ski resorts and winter sports, as well as its natural beauty, including the famous “Snow Wall” along the Tateyama Kurobe Alpine Route.

1-2: Pacific side of Hokkaido

The Pacific side of Hokkaido has a milder climate than the Sea of Japan side, with an average temperature of around 5 degrees Celsius in winter and 20 degrees Celsius in summer. The region is known for its seafood and agricultural products, including dairy products and vegetables.

2: Climate of the Sea of Japan side (excluding Hokkaido)

The Sea of Japan side of Japan, excluding Hokkaido, has a humid climate with heavy snowfall in winter and hot and humid summers.

3: Climate of the Pacific Ocean side of Hokkaido (excluding Hokkaido)

The Pacific Ocean side of Japan, excluding Hokkaido, has a milder climate than the Sea of Japan side, with an average temperature of around 10 degrees Celsius in winter and 25 degrees Celsius in summer. The region is known for its beaches, seafood, and agricultural products, including rice and fruit.

4: Climate of the central highlands of Honshu

The central highlands of Honshu have a cool, humid climate with heavy snowfall in winter and mild summers. The region is known for its natural beauty, including the Japanese Alps and the famous “Snow Corridor” in Toyama, as well as its agricultural products, including soba and apples.

5: Climate of the Seto Inland Sea

The Seto Inland Sea has a mild climate, with an average temperature of around 10 degrees Celsius in winter and 27 degrees Celsius in summer. The region is known for its islands and bridges, as well as its seafood, citrus fruit, and olive oil.

6: Climate of the Nansei Islands

The Nansei Islands have a subtropical climate, with warm temperatures year-round and high humidity. The region is known for its beaches and coral reefs, as well as its unique culture and cuisine, influenced by its location between Japan and Southeast Asia. The islands are a popular destination for diving and snorkeling.

Winter: Snow on the Sea of Japan side, clear skies on the Pacific side

The difference in weather conditions between the Sea of Japan side and the Pacific Ocean side of Japan during winter is caused by the interaction of several meteorological factors.

First, Japan is located in a region of the world where several large-scale atmospheric circulations intersect, including the subtropical high-pressure system, the Siberian high-pressure system, and the Aleutian low-pressure system. In winter, cold and dry air from the Siberian high-pressure system flows southward over the continent of Asia, while warm and moist air from the Pacific Ocean flows northward towards Japan.

Second, the Sea of Japan is a relatively narrow body of water located between Japan and the Korean peninsula. The prevailing winds in winter blow from the west towards the east, which causes the moist air from the Sea of Japan to collide with the mountain ranges on the western side of Japan. As the air rises over the mountains, it cools and its moisture condenses into snow, which falls on the plains and mountains on the Sea of Japan side.

On the other hand, the Pacific Ocean side of Japan is relatively sheltered from the cold air and moisture flowing over the Sea of Japan. As a result, the air is drier and clearer, and the sunshine can reach the plains and mountains more easily. This creates clear and sunny days on the Pacific Ocean side during winter.

Overall, the difference in weather conditions between the Sea of Japan side and the Pacific Ocean side of Japan during winter is a result of the complex interactions between large-scale atmospheric circulations, prevailing winds, and local topography.

Spring: April and May are the best months