If you are dying to see the cherry blossoms (sakura) and enjoy hanami (cherry blossom viewing), possibly while fighting all other tourists for a great photo or somewhere to sit, then I recommend going in late March/early April. If you want to try skiing in Japan, then go during winter season. Having visited Japan mostly during spring before moving here, I adored cherry blossom season and I still believe it is something everyone should experience if possible.
However, since moving here I have gotten the opportunity to experience Japan during all seasons and the autumn, with its fiery yellow and red leaves and crispy air, is a newfound favorite of mine.
So why visit during autumn?
Well, summer is incredibly hot and humid and can actually be quite crowded since a lot of people have summer vacations and choose to travel during this time. If you wait until late October and November you will be able to enjoy traveling around Japan (or stay put in one place, like Tokyo or Kyoto) in much more pleasant weather. And, you get to experience all the amazing colorful leaves (kalled koyo in Japanese)!
In autumn the vending machines are once again stocked with hot drinks (and also the all year around cold ones of course), you might be able to try sitting at a kotatsu (heating table) and also warm up in an onsen(hot spring) after a long day of exploring. The food is also great with autumn being the season for hot soups and nabe (Japanese hotpot), yakiimo (grilled sweet potatoes) and warm nihonshu (sake).
Where to go and what to expect.
When planning your autumn trip to Japan keep in mind that koyo (colorful leaves) season differs a bit depending on where you go and also if the weather is warmer or cooler than usual. Some years the color of the leaves may not be as bright and if the weather is really mild and rainy the season might be shortened, with some trees dropping leaves without them turning red.
Compared to the sakura season however, autumn color season usually lasts a longer period (about a month) and visiting sometime in November is normally a safe bet. Here is one of many koyo forecast maps, and here you can search specifically for forecasts of the area you plan to visit. The trees change color from north to south. In Hokkaido koyo is best enjoyed now in September, whereas the very south of Japan doesn't usually see red and yellow leaves until December.
Not all trees change color though. Ginko and Japanese larch turn bright yellow and different kinds of Japanese maple (momiji) go from yellow to bright red during the autumn season. A few shrubs and other trees also turn yellow or red but many trees turn brown, just drop their leaves or are evergreens (like pines and cedar trees). So depending where you go you might not find the bright reds and yellows, unfortunately not all of Japan turn bright.
Visiting Japanese gardens and going to shrine and temple grounds is a good idea since its common for ginko and Japanese maple to be planted in these kind of settings. Going hiking or walking in mountain regions is also great if you wish to see koyo.
Koyo is sort of the autumn equivalent to hanami (cherry blossom viewing) in spring and have been enjoyed in Japan for centuries. Just like spring with its sakura themes (as well as summer and winter themes for that matter) there are seasonal changes to food, product wrappings and serving ware in autumn. Momiji, the Japanese maple, is a symbol of autumn in Japan and besides from the actual tree leaves you will see the familiar motif on a variety of goods during autumn. Decorations in stores and around shopping streets (like Nakamisedori in Asakusa) as well as limited edition drinks, snacks and food packagings make the season even more colorful.
Four places to see autumn colors in and around Tokyo.
For Tokyo visitors there are a few spots that are amazingly beautiful during autumn. In Tokyo the colors start to change in November and can usually be enjoyed in early December as well. If you decide to go to Kyoto during autumn, Asha wrote a guide here.
Koishikawa Korakuen is my favorite landscape garden in Tokyo. Here the maple leaves turn a bright red in late November but even in the beginning of the month some of the maple trees slowly start to change color and it is also less crowded.
Rikugien garden is famous for its beauty during the autumn season. Although I visited the garden this previous August, when the trees were green, I could imagine the color explosion that will take place here in just a few weeks time.
Nikko is another place well worth visiting to see the vibrant colored leaves. It is a good one or two day side trip from Tokyo, with lots to see and most of the pictures in this article were shot there last autumn. The train ride takes between 1,5-2 hours so make sure to start early! My recommendation is to visit Nikko in late October or early November and to go to the small Japanese garden on the Rinnoji grunds (opposite the temple which is now being restored) and the Tamozawa Imperial Villa Memorial Park. The area around Shinkyo bridge is also a great photo spot, especially in autumn.
Icho Namiki. One of the most iconic streets for enjoying koyo since it is lined with bright yellow ginko trees. Located in Kita Aoyma not too far from Harajuku and Omotesando this is a good spot for free access to autumn colors and great for a quick detour while shopping.
If my photos above haven't made you eager to visit during this spectacular season, keep in mind that there are also festivals and other sesonal events taking place.
So what are you waiting for?
Plan your next (or first) trip to Japan during autumn and just remember to bring your camera!