After a punishing summer of unprecedented heat, Japan has introduced a new word—“kokushobi”—to describe days when temperatures hit 40°C or higher. The term, which conveys a sense of “severe” or “cruel” heat, was chosen through a public vote, reflecting how ordinary language is evolving to keep pace with extraordinary weather. What was once rare is now common enough to need its own category, as people across the country increasingly face dangerous levels of heat during the summer months.
The decision follows a year when temperatures surged past 40°C multiple times, with some regions nearing 42°C—setting new national records. Scientists say this is not an isolated spike but part of a broader pattern driven by global warming and rising sea temperatures around Japan, which trap heat and intensify conditions on land. By naming these extreme days, officials hope to make the risks more visible and push people to take heat warnings seriously, as such intense temperatures become a recurring reality rather than an exception. More