Beware the 'Heat Blast' in Japan This Summer! Record-Breaking 40°C Heatwave Sends Over 100 to Hospital in One Day

The Japan Meteorological Agency officially recorded the first extreme high-temperature event under its newly established system on the 21st, as the towns of Gujo-Hachiman in Gifu Prefecture and Tajimi City both exceeded 40°C around 2 p.m. This marks the first time the new 'Severe Heat Day' classification—defined as any day with temperatures reaching 40°C or higher, introduced in April—has been triggered.

The extreme heat is primarily caused by Japan being simultaneously affected by the summer Pacific High and the Tibetan High. This dual high-pressure system traps heat in the atmosphere, preventing dissipation. Weather Map, a meteorological information company, warned that with foehn winds affecting inland areas of the Tokai and Kanto regions, temperatures in Toyota City, Aichi Prefecture, could reach as high as 41°C, with no immediate relief in sight.

In response to the historic heatwave, the Japanese government has issued heatstroke alert warnings for 44 regions across 42 prefectures, from Okinawa to the Tohoku region—the widest warning coverage this year. The extreme conditions have already impacted healthcare systems: on the 20th alone, Tokyo Fire Department reported 162 emergency hospitalizations due to suspected heatstroke, with patients ranging from an 8-year-old child to a 94-year-old senior, most of whom were elderly.

The heat index, which combines temperature and humidity, has reached an 'extremely dangerous' level across regions from Kyushu to Tohoku, posing life-threatening risks. Meteorological authorities are urging the public to avoid outdoor activities, stay out of high-temperature environments, and spend time in cool, shaded areas. The severe heat is expected to persist until at least the 24th, with only temporary relief afterward, while hot conditions will continue.