Japan Introduces 'Kokushobi' for Days of Extreme Heat

Japan's Meteorological Agency (JMA) has introduced 'kokushobi' – translated as a 'cruelly hot' or 'brutally hot' day – to categorise days where temperatures hit or exceed 40C. This new nomenclature follows a record-shattering summer in 2023, which was the hottest since national records began in 1898, with average temperatures nationwide a staggering 2.36C above the norm.

The term was selected via a national online survey that garnered approximately 478,000 responses in February and March, with 'kokushobi' emerging as the preferred choice among 13 options. Japan already maintains specific descriptors for days surpassing 25C, 30C, and 35C, underscoring the escalating severity of heat events.

Last summer, temperatures surpassed 40C on nine separate days between June and August. The city of Isesaki recorded a new national peak of 41.8C. Major urban centres also experienced unprecedented heat; Tokyo endured 25 days over 35C, significantly higher than its average of 4.5 days, while Kyoto logged 52 such days compared to its average of 18.5. The JMA projects a high probability of above-normal temperatures for Japan this summer, from June to August, indicating that 'kokushobi' days are likely to become a more frequent occurrence.