World

Japan temperatures soar over 40C, marking first 'cruelly hot day'

BBC World · 2026-07-22

AI SUMMARY

• What happened: Japan recorded its first "kokushobi," or "cruelly hot day," as temperatures exceeded 40°C (104°F) in several cities, prompting heatstroke alerts across more than 40 prefectures. • Why it matters: This milestone highlights the increasing severity of heatwaves in Japan, with nearly 300 heat-related hospitalizations reported in Tokyo alone, emphasizing the need for public awareness and safety measures. • What to watch next: Monitor the ongoing heatwave conditions and the Japan Meteorological Agency's forecasts, as high temperatures are expected to persist into the following week.

**Japan Experiences First 'Kokushobi' as Temperatures Exceed 40°C**

Japan has officially recorded its first "kokushobi," a term referring to days when temperatures soar above 40°C (104°F). This milestone was reached on Tuesday, with central cities including Tajimi, Gujo, and Toyoda reporting temperatures that crossed this threshold. The Japan Meteorological Agency (JMA) introduced the term earlier this year in April to better communicate the risks associated with extreme heat to the public.

As the country faces an increasingly intense heatwave, the JMA has indicated that these high temperatures are likely to persist into the following week. The phenomenon is part of a broader trend of escalating extreme weather events globally, with Japan experiencing a record high temperature of 41.8°C in Isesaki last year.

Prior to the introduction of "kokushobi," Japan had already established terminology for various heat levels, including "moshobi," which denotes days exceeding 35°C. The new term incorporates the Japanese word "koku," meaning harsh or cruel, to emphasize the severity of the heat on such days.

On Tuesday, nearly 300 out of Japan's 914 weather observation points reported moshobi conditions. In response to the extreme heat, authorities have issued heatstroke alerts across more than 40 prefectures. Residents are advised to stay hydrated, utilize air-conditioning, and avoid extended outdoor activities during peak heat hours.

The Tokyo Fire Department reported a significant uptick in heat-related incidents, with 287 individuals, ranging in age from three to 103, requiring hospitalization due to suspected heatstroke. This figure marks the highest number of heatstroke cases recorded in the city this year. In light of the situation, the fire department issued an ambulance overload alert on Wednesday, urging the public to take precautions against the rising temperatures.

Japan's summers have been increasingly characterized by dangerous heat levels. A report from Kyodo News highlighted that last year, the number of heatstroke cases in workplaces reached a record 1,803, resulting in 19 fatalities. As the country braces for another scorching summer, local governments, including that of Tokyo, have encouraged office workers to adopt more casual attire, such as T-shirts and shorts, to help cope with the heat.

As the nation grapples with this extreme weather, the emphasis on public awareness and safety measures remains critical in mitigating the health risks associated with such high temperatures.

Source: BBC World
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