Yakushima Forest in September

March through May offers the most stable weather and stunning rhododendron blooms. October and November bring beautiful autumn colors with fewer crowds. Avoid June through August — it's typhoon season with oppressive humidity and daily downpours. December through February can be magical with occasional snow, but many trails close due to ice. Look, it rains year-round here, but spring and fall give you the best odds of clear views from the summit. Book accommodations months ahead for cherry blossom season in April.