In brief
Japan’s earliest-ever "kokushobi" day has temperatures soaring past 40°C, marking a new heat category for the country’s weather agency. The record-breaking heat spiked in central cities like Tajimi, Gujo, and Toyoda and is expected to linger into the coming week. Authorities have issued heatstroke alerts across 40 prefectures, urging residents to stay hydrated, use air‑conditioning, and avoid prolonged outdoor activities. Tokyo’s Fire Department reported the highest annual heatstroke admissions yet, with 287 cases that day, highlighting the public health risk. In response, Tokyo is encouraging office workers to wear lighter clothing such as T‑shirts and shorts to mitigate heat strain.
Japan experiences first "cruelly hot day" as temperatures soar over 40°C
The Japan Meteorological Agency (JMA) announced that for the first time the country felt a "kokushobi"—a cruelly hot day where temperatures rise above 40°C (104°F).
The term "kokushobi" was created in April by the weather agency to give the public a clearer warning about dangerous heat. Prior to this, Japan already used labels for days over 25°C, 30°C, and 35°C.
On Tuesday, Tajimi, Gujo, and Toyoda in central Japan topped the 40°C mark and the heatwave is projected to linger into next week, the JMA said.
The country’s previous record was 41.8°C in Isesaki last year, indicating a trend toward more intense heat events.
Heatstroke alerts have been issued in more than 40 prefectures nationwide, with officials telling residents to use air‑conditioners, hydrate, and consume salt while limiting outdoor activity.
The Tokyo Fire Department recorded 287 heatstroke cases among residents aged three to 103— the highest figure for the year— after the day’s extreme temperatures. The department also issued an ambulance overload alert on Wednesday.
Last year’s workplace heatstroke count hit 1,803 cases, with 19 fatalities, underscoring the growing danger of Japan’s sweltering summers.
In light of these risks, Tokyo’s government is encouraging workers to adopt lighter attire such as T‑shirts and shorts instead of suits and ties, a move that could reduce heat exposure during office hours.
