Hospitals across Japan treated 1,637 people for heatstroke last week, including four fatalities, the Fire and Disaster Management Agency said Tuesday.
The preliminary tally represents a more than sevenfold increase from 230 cases during the same period a year earlier, and compares with 352 cases the previous week. The agency said casualties spiked Saturday and Sunday, when temperatures topped 35 degrees in some parts of the country.
Of those taken to the hospital by ambulance, 425 people required hospitalization and 41 required stays of three weeks or more. More than 40 percent of those hospitalized were 65 or older.
The heat showed no signs of easing Tuesday as the town of Bihoro in Hokkaido recorded an all-time high of 37.2 degrees by early afternoon. It was the fourth consecutive day in which temperatures in Japan topped 35.
The Meteorological Agency issued a heat alert for most of Hokkaido and for nearby Akita Prefecture, and urged the public to take precautions against heatstroke.
The agency reported the start of the rainy season in the Shikoku region in western Japan, two days earlier than normal. The rainy season usually ends in Shikoku around July 18