As Japan swelters under its first 'cruelly hot day', with temperatures soaring above 40C in central cities, concerns are mounting over the escalating heatwave's devastating impact on public health and daily life. The designation of a 'kokushobi' marks a new level of severity for the nation, which has witnessed increasingly frequent extreme heat events.
The Japan Meteorological Agency (JMA) introduced the 'kokushobi' classification in April to convey the dangers of temperatures topping 40 degrees Celsius, previously classified as 'extremely hot days'. The distinction reflects a growing recognition of the need for precise language when communicating the risks associated with extreme heat. On Tuesday, 278 out of 914 weather stations across Japan recorded temperatures above 35C, highlighting the widespread nature of the heatwave.
The human toll of this escalating heat is stark. In 2024, heatstroke deaths surpassed 2,000 for the first time, and over 100,000 individuals required hospitalisation between May and late September last year due to heat-related illnesses. Just this week, two men, one in his 40s and another in his 70s, died in separate incidents in Niigata and Kanagawa prefectures, with heat believed to be a contributing factor.
The effects of the heatwave are far-reaching, extending beyond public health to various aspects of Japanese life. Agriculture is adapting by planting more heat-tolerant rice varieties and exploring new crops like avocados, which are not traditionally grown in Japan, to mitigate the impact on yields and quality. The national high school baseball tournament has also been restructured since 2024, splitting games into morning and evening sessions to protect players and spectators from the August heat.
Tokyo Governor Yuriko Koike's recent initiative encouraging office workers to adopt casual attire, including shorts and polo shirts, is part of the ongoing 'Cool Biz' measures aimed at reducing energy consumption and keeping workers comfortable. This move follows previous efforts to encourage 'salarymen' to forgo jackets and ties in favour of short-sleeved shirts.
Japan's long-term outlook remains concerning. The JMA reports that average summer temperatures have risen by approximately 1.3C over the last century, with both 2023 and 2024 being the hottest years on record since 1898. A 2025 study from the National Institute for Environmental Studies and Tokyo’s Waseda University warns that without significant cuts to greenhouse gas emissions, outdoor school sports could become increasingly unviable in Japan.