Event Report

Base data

Event code EW-HEW/01533/JPN
Main category Extreme Weather
Sub category heat waves
Event date (UTC) Fri, 07 Aug 2020 08:31:43 +0000
Last update (UTC) Mon, 31 Aug 2020 06:54:39 +0000


Continent Asia
Country Japan
Administration area MultiPrefectures and the Capital City
Exact location Tokyo, Chiba and Ibaraki
Open Location Code: 8Q7XMMQW+RH
Size of affected area Multi-states event
Additional events None or not detected.

Common Alerting Protocol Information

Urgency Past
Certainty Observed
Severity Extreme
Category Met

Event details

A heatstroke alert was issued for the first time for Tokyo and the two nearby prefectures of Chiba and Ibaraki on Aug. 7 as temperatures were forecast to top 33 degrees. The alert by the Japan Meteorological Agency and Environment Ministry is intended to alert residents they face an extremely high risk of heatstroke if they venture outdoors. Residents of the three prefectures were urged to stay home if they can and not exercise outdoors. The alert is a new measure introduced from this month for nine prefectures in the Kanto and Koshin regions in eastern Japan. It is based on a heat indicator that gauges when temperatures hit dangerously high levels. The indicator is calculated on the basis of temperature, humidity, and amount of sunlight. The highest danger level is set when temperatures are forecast to exceed 31 degrees. The alert is issued when temperatures exceed that danger level and are forecast to top 33 degrees. Maximum temperatures for Aug. 7 were forecast to hit 34 degrees in Kamogawa, Chiba Prefecture, 33 degrees in Tokyo’s Nerima Ward, and the Ibaraki Prefecture cities of Tsuchiura and Kashima. Many other locations were also expected to see high mercury levels of 32 degrees.

Situation update

Weather officials in Japan are urging caution against heatstroke as intense heat continues to grip wide areas of the country on Monday. The Meteorological Agency says a high-pressure system is covering western and central Japan, causing the mercury to shoot up. In some areas, the temperatures rose above 35 degrees Celsius before noon. Daytime highs are expected to hit 38 degrees in the city of Nagoya, 37 degrees in the cities of Osaka, Okayama, Saga, and Kumamoto, and 36 degrees in the cities of Hiroshima, Takamatsu, and Otsu. Intense heat has continued across the country since early August. The temperature in the city of Takahashi, Okayama Prefecture, topped 35 degrees for 22 straight days through Sunday, matching a record high for the number of consecutive days with temperatures over the mark. Many people have been taken to hospital for suspected heatstroke, with a number of deaths reported.
More than 10,000 people required medical assistance at hospitals for heatstroke for a second straight week in Japan. According to preliminary figures compiled between August 17 and 23 by the Fire and Disaster Management Agency (FDMA), 12,799 patients were taken to hospitals for heatstroke, Fuji TV reported. This number is more than double the cases compared to the same period in 2019. It is also the second straight week in which the number of people taken to hospital for heatstroke has surpassed 10,000. Among those hospitalized, 25 patients have died while 387 were seriously ill, requiring more than three weeks of medical care, the agency said. Additionally, more than half of the patients were aged 65 or older.
Officials in Tokyo say 28 people died of heatstroke in the city during the eight-day period from August 12 to August 19. That brings the total number of fatalities this month to 131. The Medical Examiner's Office says that 11 of the 28 victims were in their 70s. Ten were in their 80s. It says about 80 percent of the victims were at least 70 years old. Eleven of the victims died at night. Twenty-seven died indoors. Among the people who died indoors, 25 were not using air conditioners.
Temperatures in central Japan tied for a national record on Monday, as the country sweltered under a scorching summer heatwave. The mercury rose to 41.1 degrees Celsius (105.98 degrees Fahrenheit) in the central city of Hamamatsu, in Shizuoka prefecture on Monday, according to the Japan Meteorological Agency, matching the highest temperature ever recorded in the country, which was set in Kumagaya, a city near Tokyo, in July 2018. Japan has been enduring an intense heatwave since the middle of last week, with multiple cities and prefectures nearing 40°C (104°F) for several consecutive days. To compare, the average daytime temperature in August for Hamamatsu between 1898 and 2010 was 31.3°C (88.34°F), the JMA said. Last year, average temperatures in Japan reached the highest level since records began in 1898, and were almost a degree warmer than a typical year, according to the JMA. "Monday was a scorching hot day (like) I've never experienced, I was wearing a mask outside and drenched in sweat in the heat," said Satoru Shoji, who works at the Hamamatsu tourism office. On Monday, cities in Nagano, Gifu, Nara, Kochi and Miyazaki prefectures -- covering central and southwestern Japan -- saw temperatures above 39°C (102.2°F). Residents in the capital Tokyo broiled in 36.5°C weather, and have endured three straight days of temperatures above 35°C. Meanwhile, Osaka posted a high of 37.1°C (98.7°F) on Monday, and the popular tourist town of Kyoto reached 38.7°C (101.6°F) Of the country's 921 observation spots, 655 locations saw 30°C (86°F) weather, and 265 observed temperatures of over 35°C (95°F) on Monday. Another Hamamatsu resident who works at an eel teriyaki restaurant and gave her name as Ms. Ota, said, "I could not believe the temperature reached that high, but it feels as if a hot wind was blowing." Health officials are urging people to take precautions to avoid heatstroke and other heat-related illnesses. "Potential for heat illness is higher than usual," the JMA said in a statement, adding that people should "take appropriate measures," including drinking lots of water, staying away from direct sunlight, and using air conditioners. The hot weather is set to continue. The agency has forecast extreme highs for much of the country's south on Tuesday, with some areas forecast to reach 39°C (102.2°F). As of 11 a.m. local time, 512 locations were already over 30°C (86°F) and 41 had observed 35°C (95°F) or more. Forecasts show the heat is expected to stay until the weekend over southern Japan.

CNN Meteorologist Michael Guy said a ridge of high pressure set up in the mid-upper portions of the atmosphere was blocking other weather systems -- such as a cold front -- from pushing into the region, creating a "dome effect." "The dome effect basically creates a lid similar to a cake dish or a greenhouse and once the shortwave radiation from the sun comes through it doesn't allow for the longwave radiation to escape, allowing the heat to build over a few days," Guy said. A big danger, especially for the elderly or those with health conditions, is that during heat waves like these temperatures don't cool off at night as they usually would do, Guy said. "Above-average temperatures during the day and at night can spell trouble and cause heat stress-related ailments such as heat stroke, heart attack, and even death," he said. There are also concerns that masks worn outside to help stop the spread of coronavirus could contribute to heat-related illnesses. Japan Safe Travel, which is managed by the Japan National Tourism Organization, warned on Twitter on August 5 that, "Wearing a mask in summer with high temperature and humidity may cause heatstroke." "Therefore, if it's possible to keep a distance of at least 2 meters or more with others outside, remove your mask to avoid heatstroke." Japan's record temperatures come on the same day that Death Valley National Park, in California, potentially recorded the hottest temperature in the world since 1913. The hottest, driest and lowest national park in California and Nevada recorded a preliminary high temperature of 54.4°C (130°F) on Sunday, according to the United States National Weather Service (NWS). The all-time high of 56.6°C (134°F), reported over 100 years ago, was also recorded in Death Valley. The Western US and southwest Canada are bracing for another week of extreme heat as dozens of temperature records are expected to be broken. Nearly 60 million people in the US, from Arizona up to the US-Canada border, are under a heat advisory, watch or warning this week. Searing summer heatwaves are among the dangerous consequences of human-caused climate change. A study published in February projects that without steps to rein in heat-trapping gas pollution, as many as three-quarters of summer days across much of the Northern Hemisphere could feature nearly around-the-clock extreme heat by 2100. The study from the Chinese Academy of Meteorological Sciences, the Institute of Atmospheric Physics and other research centers found that already, compound extreme heat days -- when both daytime and nighttime temperatures are above the 90th percentile historically for that date -- are on the rise. Some scientists say these nearly nonstop sweltering temperatures will stretch our ability to adapt and in some places, could test the limits of human survivability, especially among vulnerable populations.
Officials in Tokyo say 26 people died of heatstroke in the metropolitan area over nine days through Monday, as a severe heatwave continues to grip Japan. The Medical Examiner's Office said about 80 percent of the victims were aged 70 or over. Of the 26 reported deaths, 25 occurred indoors. Twenty-two of the victims either did not have an air conditioner or had not been using one. The deaths bring the total number of fatalities from heatstroke in Tokyo this month to 79. Public health authorities are advising people to reduce the risk by using air conditioning around the clock and drinking water frequently.
The Meteorological Agency issued both heatstroke and high-temperature warnings Sunday as temperatures reached dangerous levels across the nation, breaking 40 in Shizuoka Prefecture. As of 2 p.m., the city of Hamamatsu, Shizuoka Prefecture, logged a record high of 40.9 degrees, the agency said, adding that 153 locations nationwide had already reached 35 as of noon. Record highs were also reported in Naka, Tokushima Prefecture, which hit 39, and in Kozagawa, Wakayama Prefecture, which hit 38.9. Sunday's temperatures were the first above 40 degrees since Tuesday, when the mercury hit 40.5 in Isesaki and Kiryu, both in Gunma Prefecture, and 40.2 in the town of Hatoyama, Saitama Prefecture. The heatwave saw 6,664 people enter hospitals for heat exhaustion and other related maladies from Aug. 3 to 9, nearly double the number from the previous week, the Fire and Disaster Management Agency said Wednesday. Tokyo had the most patients with 668, followed by 484 in Saitama and 417 in Aichi. A total of 10 people died of heatstroke in the period, the agency said. The heatstroke alert is a new warning system launched last month. It is being tested in the Kanto-Koshin region in eastern Japan, with an eye to rolling it out nationwide.
Japan was blanketed by sweltering heat on Sunday. Temperatures in many areas rose above 35 degrees Celsius, putting people's health at risk. It was the hottest day of the year so far in many places. In central Tokyo, the daytime high was just under 35 degrees. Warm air from the south flowed into Pacific coastal areas of eastern and western Japan. The San-in region was affected by the foehn phenomenon. Hot, dry winds blew down over the mountains, intensifying the heat. The mercury rose above 37 degrees in Shizuoka and Tottori prefectures. The Tokyo Fire Department says 38 people were taken to hospitals with symptoms of heatstroke. The heatwave is expected to continue in most parts of Japan this week. People are being advised to take precautions against heatstroke.
Japan continued to be hit by a blistering heatwave Friday with temperatures in the capital rising above 35 degrees Celsius for the first time this summer. In Shizuoka City, the mercury rose to 37.1 degrees, while Saitama City saw temperatures hit 36.4 degrees. The mercury rose as high as 35.4 degrees in central Tokyo, the weather agency here said. According to the Japan Meteorological Agency (JMA), the sweltering hit that has baked wide swathes of the country is a result of a high-pressure system spanning western to northeastern Japan bringing clear skies and soaring temperatures. The JMA said that overnight through Saturday the blistering conditions are expected to continue across wide areas in Japan, with the mercury likely to stay above the 25 degree mark, with highs of 35 degrees forecast for seven cities on Saturday. The weather agency has warned people to be careful of heat-related illnesses, including heatstroke and dehydration, and has advised people to drink plenty of water on a frequent basis. The agency also urged people amid the heatwave to make use of air-conditioners and not expose themselves to direct sunlight when outside.


Number of dead: 131 person(s)
Number of injured: 12799 person(s)
Number of Affected: 0 person(s)
Number of Rescued/evacuated: 0 person(s)
Number of Missing: 0 person(s)
Number of Infected: 0 person(s)

Event Specific Details

[Extreme Weather - heat waves]

Overview map

Risk Analisys

Nearest marine ports Tokyo Ko (5.47 km), Kawasaki Ko (22.02 km), Funabashi (23.05 km), Yokohama Ko (24.82 km), Katsunan Ko (26.04 km), Chiba Ko (35.49 km), Kisarazu Ko (39.69 km), Yokosuka Ko (45.25 km)
Nearest airports Chofu Airport (15.34 km), Tokyo Haneda International Airport (17.03 km), Iruma Air Base (30.82 km), Shimofusa Airport (30.89 km), Yokota Air Base (32.13 km), Atsugi Naval Air Facility (34.34 km), Kisarazu Airport (37.72 km)
Nearest nuclear power plant There is no known nuclear power plant nearby.

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