The Climate of Japan
Japan consists of a group of islands lying between latitudes 32 - 45 degrees north. The islands are mountainous, especially Honshu where the highest peaks rise to over 12000ft (3600m). The higher mountains in the northern islands (Honshu and Hokkaido) are covered by snow all year round.
Like its neighbours, Japan's climate is also influenced by the Asian monsoon but there are several differences between Japan and Korea or north China. Japan is separated from the Asian continent by the Sea of Japan; hence the Japanese islands have a climate modified by the sea; winters are less cold than in the same latitude on the mainland, and rain or snowfall is also much heavier.
Cold, outblowing winter monsoon winds that reach Japan from Siberia and Manchuria are warmed and pick up moisture over the sea; hence winter snowfall is more severe in northern Japan, ie. Hokkaido and the west coast of northern Honshu. In southern Japan (southern Honshu and Kyushu and Shikoku), winters are mild and almost subtropical, especially around the coasts of the Inland Sea, the narrow stretch of water which separates these islands. Winter rainfall is light here and snow and frost very rare. Most of the wet weather is caused by frontal systems which form where warm, humid air from the Pacific meets cold air from the continent.
Some parts of central and southern Japan have a double wet season: the first in early summer, called the Bai-U or plum rains, and the second in late summer and early autumn, brought by typhoons which move in from the South China Sea or the Pacific region east of the Philippines.
A few typhoons may affect Japan each year, between May and October. These normally develop in the Pacific Ocean and move northward, bringing torrential rain and strong winds with them.
In northern Japan, summers are shorter but quite warm and on the eastern coasts the summers are wetter than winter. Central and southern Japan have very warm summers, but days are seldom excessively hot. The summer heat is often sultry and oppressive, due to high humidity as Japan is surrounded by water. However temperatures are lower in the mountains, making conditions more pleasant there in the summer.
Daily sunshine amounts are only moderate in Japan due to the high humidity and abundant rainfall. Sunshine hours are lowest in northern Japan (Hokkaido and northern Honshu), about 2- 3 hours a day in winter and 5- 6 hours a day in summer. Southern Japan is sunnier with an average of 6-7 hours a day all year round. However there is less sunshine in summer than spring as summer is a wetter season. Springtime is the most pleasant season in Japan, generally warm and sunny, yet fresher and drier than in summer or autumn.
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Tokyo |
| Month |
Rainfall(mm) |
Temperature (Celsius) |
| Ave. Monthly |
Ave. No. of Days with 1mm |
Average Daily |
Lowest Recorded |
Highest Recorded |
| Min |
Max |
| Jan |
49 |
5 |
-3 |
8 |
-9 |
21 |
| Feb |
75 |
6 |
-1 |
10 |
-8 |
24 |
| Mar |
106 |
10 |
3 |
12 |
-5 |
25 |
| Apr |
136 |
11 |
8 |
16 |
-1 |
28 |
| May |
148 |
10 |
11 |
22 |
3 |
31 |
| Jun |
163 |
13 |
17 |
25 |
8 |
34 |
| Jul |
144 |
10 |
20 |
28 |
12 |
36 |
| Aug |
150 |
10 |
22 |
30 |
16 |
38 |
| Sep |
231 |
12 |
18 |
27 |
11 |
35 |
| Oct |
209 |
11 |
13 |
21 |
3 |
32 |
| Nov |
97 |
8 |
6 |
17 |
-4 |
28 |
| Dec |
58 |
5 |
2 |
11 |
-7 |
23 | |
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