In 2026, September is considered the beginning of the "secondary peak" or "silver season" in Japan. While the absolute peak tourism months are April (cherry blossoms) and November (autumn leaves), September draws significant crowds because the weather finally begins to cool from the sweltering humidity of summer. It is a transition month; early September can still be hot and is peak typhoon season, which can occasionally disrupt travel. However, by late September, the Silver Week national holidays (around Sept 21-23) create a massive surge in domestic travel, making hotels and trains very busy. For international visitors, it offers a "sweet spot" of vibrant green landscapes and the first hints of fall colors in northern regions like Hokkaido, without the extreme "over-tourism" seen during the spring.