The great diversity
Located in the northern hemisphere, Japan experiences the same seasons as Europe. However, the sheer size of the country, from the Siberian lands in the north to the tropics in the south, and its dual exposure to the Pacific and the Sea of Japan, have created varied and sometimes paradoxical climates. Two currents, one cold (oyashio) and the other warm (kuroshio), meet in both the Sea of Japan and the Pacific. The cold current descends from Siberia, while the other rises from the equator. The meeting of these two currents may well have had a major influence on the development of marine flora and fauna. But while they play a role in the development of life, the influence of the Asian landmass remains paramount. In Tokyo, cold winter winds blow from the northwest, loading up with water as they pass over the Sea of Japan and ending up as snow on the western slopes. This phenomenon explains the impressive snowfalls in the interior of Tōhoku, particularly in Yamagata, Aomori and Akita, where several meters of snow are often measured. In summer, tropical winds blow up both sides of the mountains, bringing heavy rainfall in June and September, while July and August can become very hot and humid. But the Archipelago as a whole is dominated by a huge variation in temperatures: from -30°C in Hokkaidō (the sea bordering Hokkaidō, the Sea of Okhotsk, freezes over in winter until April) to 40°C in Kyūshū or Okinawa. In some Tōhoku towns, such as Morioka or Fukushima, winter temperatures regularly dip below -10°C, while summers remain moderately warm. While winter in Tokyo is dry and cold, which makes for a fairly pleasant climate, on the other side, on the Sea of Japan, the weather remains overcast and the sky dotted with long, snowy squalls. The west coast of Tōhoku, exposed to these winds, suffers directly from their consequences.
Rainy and typhoon seasons
Although the term monsoon is more commonly used throughout Asia, it's the rainy season that prevails in Japan. Here, it's called tsuyu and generally lasts for six weeks, from June to mid-July, although in recent years it's been getting shorter and shorter... So, yes, the rain is heavy, the humidity soars and the atmosphere is muggy, but the showers are also interspersed with moments of calm. It's a risk you have to take, but they're not extreme conditions either, especially if you decide to stay in urban centers or flat areas. The Japanese summer also sees the arrival of typhoons (the equivalent of tropical cyclones or hurricanes). They strike Japan frequently between August and October, peaking in early September. Rainfall is abundant and winds violent. This phenomenon is not taken lightly in Japan, and every year, especially in rural areas, there is considerable loss of life and material damage. In addition to the typhoon itself, flooding, landslides and mudslides can be deadly. The Meteorological Agency announces the typhoon itinerary a few days in advance. Tōhoku is less exposed than the south of the country, but the Pacific coasts, such as Miyagi or Fukushima, may be affected. Other disasters can strike Japan at any time:
Volcanic eruptions. These can now be predicted, reducing the risk of loss of life. Nevertheless, the Japanese are wary of the immediate consequences, i.e. landslides and mudslides. The Zao region, between Yamagata and Miyagi, is closely monitored for volcanic activity.
Earthquakes. These are more difficult to predict, even if Japan has developed advanced technologies in this field. Earthquakes are frequent and can become formidable, especially on the Pacific slope plains, which are the most densely populated. The Kōbe earthquake killed over 6,000 people in 1995. They can cause terrible tsunamis when they occur offshore. On March 11, 2011, in the early afternoon, a powerful earthquake off Japan's east coast triggered a tsunami of rare violence, which struck several prefectures, killing tens of thousands. Tōhoku (and in particular the prefectures of Miyagi, Iwate and Fukushima) was the epicenter of this historic catastrophe. This large-scale natural disaster revealed the archipelago's shortcomings, particularly in the nuclear field, as the two Fukushima power plants were severely damaged by the earthquake. In Japan, there is a before and an after to March 11, 2011. But more than a decade later, Tōhoku continues to rebuild, between memory, reinforced prevention and resilience. On January 1, 2024, another violent earthquake (magnitude 7.6) struck the Noto peninsula region. Unfortunately, the consequences were disastrous and the region is only just recovering.
