Climate

Japan has on the whole a temperate climate, but its great length (over 3000 km) means that Hokkaido in the north is much cooler and Okinawa, the string of islands to the south of the four main islands, is subtropical. There are (as many Japanese will delight in telling you) four clearly defined seasons in Japan, with spring and autumn being the most pleasant. Winter in Hokkaido is cold and the area is under snow for about four months of the year, and summer is pleasantly cool. Okinawa is hot in the summer and pleasantly cool in winter. The remainder of the country is hot and humid in summer and cold in winter.

Clothing

In winter, you will require warm coats to keep out the icy winds except for Okinawa. In Hokkaido, be prepared for temperatures dropping to -10 degrees Celsius and more with windchill taken into account. Spring and autumn require light to medium coats, still heavy coats in the north and Hokkaido. There will be some heavy rain in summer and autumn, but largely predictable (weather forecasts tend to be very good) and hence avoidable. Summer is hot and humid, so bring light clothes, shorts, thin shirts, long sleeves if you need to cover up from the sun although summer days tend to be hazy. It can get a little cool on some days during the monsoon season. If you are heading to higher altitudes, you will need warm clothes throughout the year. Take into account the fact that the further north or the higher you go, the cooler it is.

Temperature

Japanese summers are hot and sticky. However, once you get used to them, you really appreciate air conditioning, going to the beach, swimming in rivers and many other pastimes that the Japanese indulge in during the sweltering summers to cool down. The other option is to go to Hokkaido, which is hugely popular with Japanese in the summer for its cool days and lack of humidity. Winter is cold but quite dry - exceptionally cold in Hokkaido and northern Japan, where snow covers everything for about four months of the year. At this point Japanese tend to go either to Okinawa to flee the icy days of central and northern Japan, or head for Hokkaido for some of the finest skiing in Japan, but most importantly for some of the finest food of the year. Winter in Japan ≡ Hokkaido ≡ kani (crab).

Japan's calendar is defined in terms of food: winter is the time to visit Hokkaido, but autumn is said to be the best time to enjoy traditional Japanese "kaiseki ryouri". Autumn and spring are definitely the best times to visit Japan to escape the heat and humidity of summer and the icy cold of winter, but in the summer consider Hokkaido, and in the winter consider Okinawa.

Rainfall

As you can see from the following charts, while rain falls all year round, it tends to be concentrated between June and September in most of the country, although there are variations. Rainfall is lowest in Hokkaido and the higher regions such as Nagano in the Japanese Alps. The typhoon season in August/September generally brings most of the years' rain in a few months, with periods of intense heavy rain that leads to floods and loss of life annually. However, if you are careful, there is no reason to fear the typhoon season - most deaths are connected with rivers carrying away unlucky campers. Winter snowfall is greatest on the western coast of Japan.