Whilst temperatures in Tokyo, Kyoto and across most of Honshu remain high in September (avg temp: 23-25°C), days can be punctuated with intense periods of rainfall driven by the typhoons that hit the southern islands during the month. Infact, September is the wettest month of the year in Tokyo.

September in Japan is a month of transition, often feeling like an extension of summer but with noticeably fewer crowds. In early September, temperatures in central cities like Tokyo and Osaka remain high (around 28°C to 32°C) with high humidity, making light, breathable clothing essential. However, by late September, the air begins to crisp, especially in northern Hokkaido, where the fall foliage (koyo) starts to appear. A major consideration for September travel is Typhoon Season; while they rarely cause dangerous situations for tourists, they can lead to flight or Shinkansen delays, so flexible planning is advised. Culturally, the month is famous for "Tsukimi" (moon-viewing) festivals and the thrilling Kishiwada Danjiri Matsuri in Osaka, where massive wooden floats are raced through the streets. It is an ideal time for hikers, as the mountain trails are open and the scenery is lush and green before the autumn shift, though you should be prepared for sudden rain showers.