Japan
spans a great distance from north to south so while the entire nation receives
a temperate climate with all for seasons, the far south is sub-tropical while
the far north is cool continental. Adding to the large regional climate
variations are the mountains, which cover most of the country, the huge Asian
continent to the west and the Pacific Ocean to
the east. Despite being an island nation, surrounded by water, Japan
sees huge differences in temperature from summer to winter, which is more
characteristic of a continental climate. Japan is affected by many typhoons
and rainfall is high throughout the country. Most of Japan receives a pronounced rainy
period in June and July.
Japan is
made up of volcanic islands and is part of the Pacific Ring of Fire; Japan is home
to ten percent of the world’s active volcanoes. The country is highly fertile
and mountainous, receiving many earthquakes which sometimes lead to tsunamis.
As a result of the steep terrain urban areas have grown up around the flatter
coastal areas with dense forest covering the majority of Japan; Japan’s cities are the most densely
populated in the world. Japan’s
large islands, from north to south, are Hokkaido,
Honshu, Shikoku and Kyushu, to the south of which lie the much smaller Ryukyu Islands.
Hokkaido
The northernmost island
of Japan receives a cool
continental climate with warm rather than hot summer and cold winters. It is
the island nearest to Russia
which gives a good idea of its seasonal weather as the island is greatly
affected by weather systems coming over from the continent. Precipitation is
generally moderate all year, though in winter this translates to high snowfall.
There is a great deal of regional variation; areas closer to the sea receive
milder temperatures, with warmer winters and cooler summers, than inland
locations, while as elevation increases in the mountains temperatures become
colder throughout the year. Sapporo, on Hokkaido’s west coast,
is hottest in August with an average high of 26°C and an average low of 19°C,
when it is also at its wettest. It is coldest in January with an average high
of -1°C and an average low of -9°C. Further north and inland the gourmet town Asahikawa is at a
slightly higher elevation and so receives similar summer temperatures, but its winters
are much colder with an average high of -5 and an average low of -14°C in
January. It snows almost every day in winter all over the island and skiers
flock to Hokkaido’s
mountains, six of which are active volcanoes.
Honshu
Honshu is the largest of Japan’s
islands and as such its climate is very similar to that of Hokkaido in the north, while its southerly
regions are subtropical. The Japanese Alps, including Mount
Fuji, see much cooler conditions and create large regional
differences in climate from northeast to southwest. Northeast regions tend to
receive a more even distribution of rain throughout the year, coming gradually
to two peaks: one in late summer and one in mid winter. Along this coast
rainfall increases towards the southwest. Northeast regions also tend to have
colder, snowier winters. Southwest regions receive a pronounced wet season from
June till September; high levels of rainfall ease off in the dry season and
actually reach quite low levels in winter months. Southwest winters are clearer
with less snow. Temperatures increase across all seasons from north to south
and hotter regions receive heavy thunderstorms in the summer months.
Aomori, in the northernmost
part of Honshu, is hottest in August with an average high of 27°C and an average
low of 19°C, just one degree warmer than Sapporo
on Hokkaido.
It is coolest in January with an average high of 0°C and an average low of -6°C,
about three degrees warmer than Sapporo.
Much further south, in the middle of Honshu’s east coast, Tokyo sees an average high of 31°C and an
average low of 24°C in August. Winters in Tokyo
are incredibly mild with an average high of 10°C and an average low of 0°C in
January. Low humidity in this region allows for the dramatic drop in
temperature from day to night. On the opposite coast, to the west of Tokyo, Kanazawa
sees a much smaller difference in winter day and night temperatures with an
average high of 6°C and an average low of 0°C. This is due to the higher
humidity allowing for better insulation, while the lower average high can be
attributed to cold air coming over from the continent. Up in the low mountains,
Nikko receives
slightly cooler summers around 25°C in August and cold winters with an average
low of -8°C. Higher up, the Japanese Alps receive a very cold climate; their
peaks are covered in snow for many months from autumn into late spring and
summers are often stormy.
Shikoku
This is Japan’s
smallest major island. It is as mountainous as the other islands but is the
only one without an active volcano. The mountains run from east to west,
splitting the island into a small, northern region facing the Inland
Sea where most of the population is located, and a considerably
larger southern region facing the Pacific, which is very mountainous. The island’s
mountains block wind from the Pacific and so the south side is highly
precipitous while the northern region is quite dry. The climate is temperate;
due to its small size the moderating effects of the sea are more pronounced.
Summers are warm to hot and winters are mild, rarely seeing snow at sea level.
The high mountains are much cooler.
Kyushu
Kyushu, the southernmost of Japan’s major islands, receives a
sub-tropical climate with long, hot summers and mild winters. The wet season
falls in the summer months with rainfall very gradually increasing as the
season approaches and very gradually decreasing after its peak. It is driest in
December, wettest in June and sees huge amounts of rain between April and
September. Rainfall increases from north to south. Nagasaki,
in the north, sees summers similar to those in Tokyo, with an average high of 31°C in
August. Winters are much milder here; January sees an average high of 9°C, an
average low of 3°C and it rarely gets down to freezing, though frosts aren’t uncommon.
The sea around Kyushu is generally warm enough
for swimming year round if you’re prepared to be a little brave in the winter
months.
Ryukyu
Islands
These islands, south of Kyushu’s
southern tip, stretch all the way down to the equator and as such you will find
sub-tropical climates in the northern islands, and true tropical climates in
the southern islands. Naha, a town on one of the
central islands, receives a similar rainfall pattern to Japan’s major
islands. Its temperature is much warmer in the winter, around 19°C,
temperatures above 20°C last for the rest of the year, getting above 30°C from
July till September. As per usual, mountainous regions are much cooler.
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