When it comes to exploring japan, a lot of walking is a given. Even in well connected cities like tokyo, kyoto and osaka, the fastest, best way to explore is typically by. What to wear in japan in summer (june/july/august) japan’s rainy season starts at the beginning of june. After that, the real summer begins and does not only bring high. Rain or shine, july is hot for the most part, and. The following packing list has been submitted by emily lessnau. See all packing list posts here. Summer in japan is a double edged sword. You get beautiful flowers, fantastic. In japan's summer, which is from june through august, the weather gets fairly hot right after the rainy season in june finishes up.