Japan has like most part of the world four seasons. The weather can vary enormously if you look at the whole country, from Hokkaido in the north to Okinawa in the south.
This post focuses on the weather in Tokyo, where the winters are relatively mild, between 0-10 degrees C (32-50 F) and often sunny. Summers are hot and humid, around 28-35 degrees C (83-95 F). Spring and autumn, from March to May and late September to early November are relatively mild and pleasant, alternating between 5-25 degrees C (41-77 F).
Winters in Tokyo is often relatively mild and dry. The temperature is between 0-10 degrees C (32-50 F) and the number of rainy days is really low. Something to consider is that Japanese houses are quite cold (before you get the heating going) and it’s often about the same temperature inside as outside. This is no problem if you live in a hotel, but if you are planning a longer stay and planning to rent an apartment or similar, it might be good to bring warm nightwear.
The clear winter air is also good for those who want to get a glimpse of Mt.Fuji from Tokyo. Almost an impossibility in the summer. On occasion it snows in Tokyo, it’s rare and when it snows it usually doesn’t stay for that long.
Spring: March to May
During spring the weather is getting gentler quite quick, the trees begin to bloom and you can start to remove those warm outer layers. A definite highlight in the spring is, of course, the cherry blossoms. The city gets populated with a pink fluffy tree that we all know from the pictures. Before the cherry trees are in full bloom one can see the dark pink and almost purple plum trees blossoming in the city. Not as pompous but good nevertheless. Timing the cherry blossom can be a bit tricky and requires som degree of luck if you are planning a shorter stay. The trees bloom during a one to two week period and this usually happens sometime in mid-March to early April, depending on the temperature. If you time it well you probably will get to see the traditional Hanami (flower watching). People gathering underneath the trees to share drinks and food.
In May “Golden Week” happens, a number of holidays that concur during the same week, on April 29 and 3-5 May. This week all (well, most) Japanese people go on vacation, at the same time, 128 million people, at the same time. This week will be crowded and expensive, avoid if you can.
Summer in Japan is hot and humid, if you can’t stand the sticky humid heat, you should avoid July, August and early September. This time also sees a lot of rain and thunderstorms.
Something you do not see at any other time other than summer is festivals and fireworks. Festivals or “matsuri” occurs throughout the year but are more concentrated around the summer months. Matsuri is often associated with local temples, where a mobile part of the temple, called Mikoshi, is carried or rolled through the streets. In and around the festival area, street food is served, there are games for children etc. Fireworks are limited to the summer. One reason is the humid weather, which minimizes the risk of fire, unlike the dry winter where the risk of fire is greatest in Japan.
Autumn: September to November
The fall months can be really beautiful and comfortable weather wise. The leaves of the trees are changing and they display a beautiful range of colors, from green to dark red. There is a slight risk of rain, though.
When should you go?
It clearly depends on what preferences you have. I think that spring and fall are the best times, the weather is pleasant, often around 20 degrees C (68 F). Some like the crisp sunny winter months, which definitely has its advantages. If you are a person who thrives in hot, humid weather then the summer is your best bet.
Have a nice trip!