Japan has issued a public alert after record-breaking early-summer heat enveloped much of the country this week and four people died from suspected heatstroke.
The Kanto–Koshin region recorded temperatures above 35C at 65 observation points, with Kofu touching 38.2C, Takasaki 37.7C and Shizuoka 37.6C.
In all, at least 547 locations in the country recorded temperatures over 30C this week, including Tokyo at 34.8C and Osaka at 33.4C.
“The current heat is clearly unusual,” Yukiko Imada, professor in the University of Tokyo’s Climate System Research department, told the South China Morning Post.
The four people who died of heatstroke were all elderly and included a woman aged 96 who was found collapsed in a field in Gunma and later pronounced dead.
Tokyo hospitals treated 169 people for heatstroke symptoms on 18 June and a further 57 the next day, demonstrating mounting strain on healthcare services.
Authorities have warned that above-average heat is likely to continue through the weekend and have set up more than 500 temporary cooling shelters in affected areas. Emergency services are urging people, particularly the elderly, to stay indoors, hydrate regularly, and avoid unnecessary outdoor activity.
Forecasters predict the heatwave to last until the end of this week. They say that clear skies and weak winds driven by a strong Pacific high-pressure system are responsible.
The meteorological agency has forecast that summer 2025 is likely to be “above normal” in terms of temperature, raising concerns of further extreme heat events in the months ahead.
The heatwave arrives on the heels of last year’s record-breaking summer, the hottest in Japan since records began in 1898. Average summer temperatures in 2024 were 1.76C above the 1991-2020 norm and over 120 people died from heatstroke in Tokyo alone in July 2024.
Experts say these extreme early-season heatwaves may intensify with climate change.
