Catharina Klein
Research expert covering Japan
Weather in Japan - statistics & facts
Japan hosts contrasting climate regions, varying from a humid continental climate in the north to a subtropical climate in the south. The archipelago has four distinct seasons, but the weather conditions differ between the Pacific side and the Sea of Japan side. While northern Japan has warm summers and cold winters with snowfall occurring in mountainous areas on the Sea of Japan side, the southern areas tend to have very hot and humid summers and moderately cold to mild winters.
The average annual rainfall stood at around 1.77 thousand millimeters in recent years. Most of the rain fell during the rainy season, which is the time of year when most of a region's average annual rainfall occurs. In most of Japan, the rainy season lasts from early June to mid-July. In Okinawa, it roughly starts a month earlier, but northern regions such as Hokkaido are less influenced. Furthermore, heavy rain is often caused by typhoons, which regularly approach the archipelago between July and October. Typhoons develop over the Pacific Ocean and are likely to approach Japan's southern prefectures, while Hokkaido is the least affected area.
Global warming already affected the archipelago in recent years, leading to an increase in average temperatures and a higher frequency in extreme weather situations like typhoons, heavy rainfall, and temperatures above 35 degrees. This resulted in increased health problems of citizens such as heat strokes as well as higher damage costs due to natural disasters. To counter global warming, Japan currently aims to increase its renewable and nuclear energy share to reduce its carbon footprint.
Seasonal weather in Japan
Due to tropical airflows from the Pacific Ocean and Southeast Asia, Japanese summers are characterized by high temperatures and humidity. The monthly mean air temperature in the capital Tokyo usually peaks in August, reaching over 27 degrees Celsius. In Okinawa, temperatures increase to over 28 degrees Celsius between July and September, while Sapporo, the capital of the northern main island Hokkaido, only reaches about 24 degrees Celsius in July. January tends to be the coldest month on the archipelago. Heavy snowfall mostly occurs in mountainous regions on Hokkaido as well as northern parts of Honshu which face the Sea of Japan. In contrast, the southern prefectures rarely experience snow.The average annual rainfall stood at around 1.77 thousand millimeters in recent years. Most of the rain fell during the rainy season, which is the time of year when most of a region's average annual rainfall occurs. In most of Japan, the rainy season lasts from early June to mid-July. In Okinawa, it roughly starts a month earlier, but northern regions such as Hokkaido are less influenced. Furthermore, heavy rain is often caused by typhoons, which regularly approach the archipelago between July and October. Typhoons develop over the Pacific Ocean and are likely to approach Japan's southern prefectures, while Hokkaido is the least affected area.
Natural disasters and extreme weather
Since Japan is situated along the Ring of Fire, an area where several tectonic plates meet, it is vulnerable to natural disasters such as earthquakes, tsunamis, and volcanic eruptions. As typhoons regularly cause heavy rainfall, residential buildings often get damaged due to flooding.Global warming already affected the archipelago in recent years, leading to an increase in average temperatures and a higher frequency in extreme weather situations like typhoons, heavy rainfall, and temperatures above 35 degrees. This resulted in increased health problems of citizens such as heat strokes as well as higher damage costs due to natural disasters. To counter global warming, Japan currently aims to increase its renewable and nuclear energy share to reduce its carbon footprint.
