Land and Resources, Climate
baiu, typhoon damage, central Honshu, Monsoon winds, Ryukyu Islands
Japan’s climate is rainy and humid, and marked in most places by four distinct seasons. The country’s wide range of latitude causes pronounced differences in climate between the north and the south. Hokkaido and other parts of northern Japan have long, harsh winters and relatively cool summers. Average temperatures in the northern city of Sapporo dip to –5°C (24°F) in January but reach only 20°C (68°F) in July. Central Japan has cold but short winters and hot, humid summers. In Tokyo in central Honshu, temperatures average 3°C (38°F) in January and 25°C (77°F) in July. Kyushu is subtropical, with short, mild winters and hot, humid summers. Average temperatures in the southern city of Kagoshima are 7°C (45°F) in January and 26°C (79°F) in July. Farther south, the Ryukyu Islands are warmer still, with frost-free winters.
The climate of Japan is influenced by the country’s location on the edge of the Pacific Ocean and by its proximity to the Asian continent. The mountain ranges running through the center of the islands also influence local weather conditions. The Sea of Japan side of the country is extremely snowy in winter. Cold air masses originating over the Asian continent absorb moisture as they pass over the Sea of Japan, then rise as they encounter Japan’s mountain barriers, cooling further and dropping their moisture in the form of snow. The heaviest snows are in Nagano Prefecture, where annual accumulations of 8 to 10 m (26 to 30 ft) are common. By contrast, Pacific Japan lies in a snow shadow on the sheltered side of the mountains and experiences fairly dry winters with clear skies.
From June to September this pattern reverses. Monsoon winds from the Pacific tropics bring warm, moist air and heavy precipitation to Japan’s Pacific coast. A month-long rainy season called baiu begins in southern Japan in early June, traveling north as the month progresses. Baiu is followed by hot, humid weather. In late August and September, the shurin rains come to much of the country, often as torrential downpours that trigger landslides and floods. During this period, violent storms called typhoons come ashore in Japan, most often in Kyushu and Shikoku. Japan’s distant tropical islands also suffer typhoon damage. Meanwhile, throughout the summer the Sea of Japan coast is protected from the Pacific influences by the mountains and is relatively dry. Northern Honshu and Hokkaido receive relatively little summer precipitation. Average annual precipitation in Sapporo is 1,130 mm (45 in), while in Tokyo it is 1,410 mm (55 in) and in Kagoshima it is 2,240 mm (88 in).
Autumn and spring are generally pleasant in all parts of Japan. The season when cherry blossoms open (typically late March to early May, depending on latitude and elevation) is particularly festive.
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