TOKYO — Japan is experiencing one of its worst heatwaves ever, raising concerns about potential power shortages amid rising demand, even as officials urged people to leave their air conditioners on to avoid heat stroke.
In Tokyo, temperatures rose above 95 degrees on Saturday for the eighth day in a row, an increase the capital has seen only once since 1875, when data records began. Scorching heat has descended on cities across Japan, such as Isesaki in Gunma Prefecture, which passed 104 degrees on Friday, nearly breaking a record set just two years ago.
A number of deaths have been attributed to the heat, as has an increase in people being treated for heat stroke and exhaustion. More than 4,500 people with such symptoms have been taken to hospitals by ambulance in recent days, according to Japan’s Fire and Disaster Management Agency, more than four times the number in the same period a year ago.
Most of those patients were 65 years of age or older. Seniors, who are particularly vulnerable to extreme heat, make up a disproportionate share of Japan’s aging population.
Authorities have been issuing daily heat warnings for a week, asking people to stay indoors as much as possible and use umbrellas to protect themselves from the sun. Officials have also urged people not to wear face masks, which most residents of Japan have been painstakingly using during the Covid pandemic, in many outdoor situations.
“I would like to ask people to take off their masks when they walk, jog and cycle to work,” Seiji Kihara, the deputy cabinet secretary, said Friday.
Energy companies have warned that the heat wave would put pressure on the grid, although there had been no outage as of Saturday. Tohoku Electric Power Company, which serves six prefectures in northern Japan, said this week it would be “extremely difficult” to keep electricity flowing for all of its customers. “Please save as much power as possible,” the company said.
Prime Minister Fumio Kishida and other officials have urged people to keep their air conditioning on for their own safety but cut back on other uses of energy. “Most of the lights in my office are off,” Tokyo governor Yuriko Koike said at a news conference Friday. “It is dark.”
Ms. Koike suggested turning refrigerators to higher temperatures and turning off the heated toilet seats that are popular in Japan. (“Under these circumstances, you can turn it off completely,” she said.)
Japan is vulnerable to power outages during periods of high demand because it relies heavily on liquefied natural gas, which is difficult to store and has become more expensive since Russia invaded Ukraine in February. Japan has kept most of its nuclear power plants closed since the Fukushima meltdown in 2011, and has closed coal-fired power plants to reduce CO2 emissions.
Japan’s economy ministry said on Friday that the heat wave is likely to ease rapidly, along with pressures on electricity supplies. “Next week, the heat is expected to decrease and the demand for power will also be less,” the statement said.
On Twitter, some people said they found ways to deal with it. Yoko Koguchi, a Tokyo politician, said her daughter’s catchball practice had been canceled due to the heat. “Thanks to this free time, we’re going to a bookstore and a short trip for something tasty,” she said. “I’ve heard an umbrella was effective, so we use a large one.”
Others focused on urging people to take care of themselves. “You can’t handle the heat with just your stamina. No matter how strong you are, you can lose your life,” said Kentaro Araki, a researcher at the Japan Meteorological Agency. “Please take all possible measures to protect your life.”
Hisako Ueno reported from Tokyo, and Karan Deep Singh from Seoul.