Japan Logs First 40C 'Cruelly Hot Day' as Tokyo Heatstroke Cases Hit 287
Updated
Updated · BBC.com · Jul 22
Japan Logs First 40C 'Cruelly Hot Day' as Tokyo Heatstroke Cases Hit 287
3 articles · Updated · BBC.com · Jul 22
Summary
Three central Japanese cities—Tajimi, Gujo and Toyoda—reached 40C on Tuesday, marking the country’s first officially designated “cruelly hot day” under a new weather-agency warning category.
287 people aged 3 to 103 were taken to Tokyo hospitals for apparent heatstroke the same day, the city’s highest tally this year, prompting an ambulance overload alert on Wednesday.
Nearly 300 of Japan’s 914 observation points recorded at least 35C, and heatstroke alerts were issued across more than 40 prefectures as the Japan Meteorological Agency said the heat will persist into next week.
The new 40C label was introduced in April to sharpen public warnings as Japan’s summers grow more dangerous; last year workplace heatstroke cases hit a record 1,803, including 19 deaths.
Japan just officially named its 'cruelly hot days.' Are its cities fundamentally built to survive them?
With nights warming faster than days globally, is the greatest health risk from heat now happening after sunset?
2026 Japan Heatwave: Surpassing 40°C and the Rise of “Kokushobi” in a Warming World
Overview
In the summer of 2026, Japan faced an unprecedented heatwave that marked a new climate reality for the nation. On July 21, three central cities experienced their first 'kokushobi'—a new term introduced by the weather agency to warn the public about days when temperatures reach a dangerous 40°C. This extreme heat was widespread, with hundreds of observation points across Japan recording high temperatures. The event highlighted the urgent need for better public alerts and adaptation strategies, as the country grapples with increasingly severe and frequent heatwaves driven by both meteorological factors and long-term climate change.