Heatstroke cases surge across Japan as the country battles one of its most severe summer heatwaves in recent years. In just one week, 10,857 people were rushed to hospitals by ambulance between July 13 and July 19, according to Japan’s Fire and Disaster Management Agency. The figure marks the first weekly total above 10,000 since monitoring began on May 1, and is 2.4 times higher than the previous week’s 4,580 cases. It is also more than double the 4,958 heatstroke-related hospitalizations recorded during the same period in 2025, underscoring the growing public health threat posed by extreme temperatures.

Authorities confirmed 14 deaths, while hundreds remain in serious condition as temperatures continue to shatter records across the country.

Elderly Population Bears the Brunt

The latest data highlights that older adults remain the most vulnerable.

• People aged 65 years and above accounted for 6,734 cases, representing 62% of all hospitalizations.
• Among the patients, 321 people were classified as seriously ill, requiring at least three weeks of hospitalization.
• Around 37% suffered moderate symptoms, while nearly 59% experienced mild heatstroke.
• Interestingly, homes emerged as the most common location for heat-related illnesses, with 4,523 cases, followed by roads (2,326) and public outdoor spaces (1,095).

Health officials warn that many elderly individuals avoid using air conditioners despite dangerous indoor temperatures, significantly increasing their risk.

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Record-Breaking Temperatures Fuel the Crisis

The heatstroke cases surge across Japan coincides with unusual temperatures across several prefectures. According to the Japan Meteorological Agency (JMA), 41.1°C was recorded in the Sakuma district of Hamamatsu, Shizuoka Prefecture, making it the highest temperature recorded in Japan this year.

Several regions including Nagoya, Gifu, Kyoto, and Kofu were forecast to reach 40°C, with Gifu and Kyoto potentially experiencing such temperatures for the first time in recorded history. Meanwhile, parts of the Tokai region endured temperatures above 40°C for three consecutive days, while nighttime temperatures remained above 30°C, reducing opportunities for the body to recover from daytime heat.

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Tokyo and Osaka Witness Sharp Rise in Emergencies

• Osaka recorded the highest number of ambulance transports (1,041) among Japan’s 47 prefectures, followed by Aichi (797) and Tokyo (783).
• Tokyo’s weekly total was more than double last year’s equivalent figure of 379 cases.
• On Wednesday alone, the Tokyo Fire Department transported 453 people to hospitals due to heatstroke, the highest single-day total since records began in 2010.
• Emergency officials also confirmed one death and four critically ill patients in Tokyo during the same day.

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Authorities Urge Immediate Precautions

With heatstroke alerts issued across 39 prefectures, covering regions from Kanto to Okinawa, authorities continue urging residents to stay indoors in air-conditioned environments, avoid unnecessary outdoor activities, and drink water regularly before feeling thirsty. Officials are especially advising extra care for older adults, young children, and individuals with underlying medical conditions, who remain at the highest risk as Japan’s relentless heatwave shows little sign of easing.

Japan Heatwave at a Glance