Japan logs first kokushobi day above 40C
Meteorological agency adds new heat warning term as hospitalisations and power strain rise, baseball schedules and office dress codes adjust before emissions do
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Japan’s meteorological agency coined the term kokushobi – or “cruelly hot day” to warn the public of dangers tied to extreme heat. Photograph: Nicolas Datiche/SIPA/Shutterstock
theguardian.com
Japan recorded its first official “kokushobi” on Tuesday, the new label the Japan Meteorological Agency uses for days when temperatures exceed 40C, The Guardian reports. Three cities—Gujo and Tajimi in Gifu prefecture and Toyota in Aichi—hit the threshold, with Toyota setting a local station record at 40.1C. Across the country, hundreds of weather stations logged “extremely hot days” above 35C.
Japan has long treated heat as a seasonal inconvenience managed with etiquette and air-conditioning, but the state is now inventing vocabulary to push people into different routines. The term “kokushobi” was introduced only in April 2024, a bureaucratic attempt to make the risk legible in a society where many still work outdoors, commute in packed cities, and live in ageing housing stock. The Guardian notes that heatstroke deaths topped 2,000 for the first time in 2024 and that more than 100,000 people were taken to hospital last year over the summer months, figures that turn a weather story into a health-system load.
The adaptation is spreading into places where Japan’s social contract is most visible: schools, offices, and food security. The national high school baseball tournament at Koshien has been split into morning and evening sessions since 2024 to reduce heatstroke risk, a change that rewrites a national ritual around the day’s temperature curve. Tokyo governor Yuriko Koike has expanded “Cool Biz” guidance to include more casual clothing, framed not only as comfort but as a way to manage electricity supply challenges when air-conditioning demand spikes.
Agriculture is absorbing the same heat as the cities. The Guardian reports that rising temperatures are affecting rice yields and quality, pushing farmers toward heat-tolerant varieties and even different crops. That matters in a country where rice is both staple and symbol; quality loss is felt in household budgets and in the export branding of premium regional varieties.
Japan’s meteorological agency says average summer temperatures have risen about 1.3C over the past century, and the country has logged consecutive record-hot years. A 2025 study cited by The Guardian warned that without steep emissions cuts, school sports could become unplayable outdoors by the 2060s.
On Monday, a man in his 40s was found dead on a street in Niigata, and another man in his 70s died in Kanagawa, both believed to have succumbed to the heat. On Tuesday, the new word for “cruelly hot” entered the daily forecast as a practical instruction.