Originally Posted by
evergrn
Either one's fine. Nov-Apr is probably the best time to visit Tokyo weather-wise. Early-summer starts to get hot with more rain, July~Sept is very muggy, you can get typhoons from late summer through Oct.
You can expect the most sun, driest weather, and clearest sky in winter. Winter in Tokyo is not that bad... certainly far easier to bear than summer time. But as others have said, the cherry blossom in Mar~Apr will be a nice thing, plus it should be warmer.
I'd extend that to Oct to May. May is very nice weather and not as busy as other times, as Golden Week holiday has finished and many are well involved in school and work life. Rainy season will likely start in June. However, it's not rainy all the time and June can also be a great time for travel in Japan. Oct is a very busy time for Japanese families (school activities, popular wedding season), but is also great weather, as the heat of the summer has passed.