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Japan's summers are getting too damn hot! And why it's likely they'll get even hotter

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Japan's summers are getting too damn hot! And why it's likely they'll get even hotter.

The summer of 2023 was Japan's hottest on record. Central Tokyo posted 64 days in which temperatures exceeded 30 degrees Celsius. Fukushima and Ishikawa Prefectures recorded highs of over 40 degrees.

What's in store for this year?

Weekly Playboy (July 29) turned to Professor Yoshihiro Tachibana of Mie University, whose laboratory researches weather and climate dynamics.

One thing the country can expect this summer will be greater damage from torrential rains.

Tachibana also predicts the weather will alternate between hot, sunny days, described with the term shakunetsu jigoku (incandescent hell), alternating with episodes of sudden, unexpected "guerrilla downpours."

Tachibana tells the magazine that the normal pattern in the past has been for the westerly winds from mainland Asia to flow straight in an easterly direction, sometimes wobbling slightly. The temperatures to the north of the westerlies are cold, and those to the south are warmer. Since Japan lies in the path of such winds, a wobbling effect can cause temperatures on both sides to become more extreme.

Over the past several years, moreover, the flow of the westerlies has continued to shift northward, above Hokkaido, and thereby preventing cooler air from flowing southwards and conversely allowing hot air from the south to cover the entire archipelago.

What's the cause of this? As temperatures rise in the Arctic, the disparities between temperatures here and at the equator decline, which is believed responsible for the extreme wobbling of the westerlies. And Japan's geographic position between the Asian continent and the Pacific also facilitates the westerlies to shift northward.

Japan is surrounded by ocean, so it stands to reason that when air currents above the ocean flow over the land, it becomes hotter.

Another reason for this warming trend is the major wobbling of the Kuroshio (Japan current). The current flows north from the Philippines, and as it nears Yakushima off Kyushu redirects eastward and then after reaching the Boso Peninsula of Chiba veers into the Pacific. More recently, however, it has begun to cling to the coastline of Honshu as far as Hokkaido, and ocean temperatures similar those around Kyushu have risen along the entire Pacific coast.

When the seas off Hokkaido become warmer, rainfall increases.

"Water vapor generated from from the sea cools in the atmosphere, causing rain. As ocean temperatures in the seas adjacent to Japan have been abnormally high, when the moist air flows inland and collides with low-pressure systems it becomes easy for heavy downpours to occur all over the country," Tachibana warns.

He calls for an effective alert system for these "guerrilla downpours" to be put into operation, particularly in the Kanto and Tohoku regions along the Pacific side of the archipelago.

In 2024, there's yet another factor at work: This year's El Nino has ended and from around the start of summer La Nina has appeared. During such summers it is easy for Japan to encounter extreme heat, and this year's temperatures are expected to exceed those of last year.

Needless to say, such heat is likely to exert major impacts on people's lives.

"The sanma (pacific saury) catch has been extremely low. Once it was a fish on everyone's table; now it promises to be a luxury item," Tachibana points out.

The widely consumed Koshihikari strain of rice will decline in quality, with major producing areas such as Niigata Prefecture likely to suffer a heavy blow. If the temperatures match or exceed last summer's, it will possibly affect crop output as well. Likewise for vegetables. Low yields will see higher consumer prices.

"Our regular diets might be forced to change due to weather extremes," Tachibana predicts, adding, "On days of extreme heat of over 35 degrees, I think companies and schools should shut down. And for people who work out of doors, this can be a matter of life or death."

According to Ministry of Health, Labor and Welfare, fatalities from heatstroke generally run about 1,000 per year, but Tachibana expects these to increase.

As a countermeasure, this year local governments will be issuing "special heatstroke alerts," and communities have been setting up "cooling shelters" where overheated residents can go to cool down. They include special corners in city offices, libraries and other public facilities, drugstores and shopping centers.

Check out where these islands of safety are, Weekly Playboy advises. Finding a place to flee from the incandescent summer heat may very well save your life.

© Japan Today

©2025 GPlusMedia Inc.

15 Comments
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I am so very grateful to be living near the coast in California. Mild winters, beautiful summers. So sorry about everyone who is suffering while living elsewhere.

1 ( +6 / -5 )

It's been pretty good in Kumamoto so far: LOTS of rain (I'm worried about the farmers) and cloudy days. 1glenn, I gotcha. I grew up a short distance from the beach, and my mother didn't even have air conditioning.

3 ( +4 / -1 )

 Mild winters, beautiful summers. 

@1glenn I'm happy for you, but I seem to recall all kinds of news reports about weather extremes in California, including high temperatures, prolonged heavy rains, huge brushfires, and others. Nice that you reside in a place that has been spared the worst of it, but we're all on the same planet and I'm not sure how much longer the good times will continue.

8 ( +8 / -0 )

We've had rain all but two days of July. Lots of heavy bursts too, which wreck the flowers in my garden.

It got up to 34C one day, but not so hot so far. Just extremely wet, even by rainy season standards.

Rain map vs. average for July.

https://www.data.jma.go.jp/obd/stats/data/mdrr/tenkou/indexTenkou.html?gazou=pre20d00&dhi=0

2 ( +2 / -0 )

Maybe if we could open a hole in the high atmosphere all the gunk that's making it hot will filter out in to space. Until then, it's been knowing everyone. Maybe our dead bodies can at least feed the last surviving creatures on earth before they, too, die.

Dang. We have to be the victims of the 6th great extinction. It's only unbearable now. Wait till it get worse.

2 ( +6 / -4 )

I am so very grateful to be living near the coast in California. Mild winters, beautiful summers. So sorry about everyone who is suffering while living elsewhere.

In many ways I miss California, the magnificent food, and the weather, just can't be beaten. Grew up in OC and the beaches were always the best, especially Newport and Huntington Beach, just the best, on that alone you are definitely lucky.

-7 ( +4 / -11 )

Firstly, remove the stupid masks from your faces and chins. You will be a lot more comfortable in this humidity!!!

1 ( +11 / -10 )

Huge shock that the comments section is filled with Californians.

Anyway, the weather is definitely alternating between extreme heat and extreme downpours.

0 ( +3 / -3 )

As someone from south Georgia in the US, Japanese summers still have a ways to go. I've been in weather where the ground and roads get so hot that they will steam as it is raining - rain and evaporation at the same time.

1 ( +3 / -2 )

the problem with california is the conversation trails off quickly after talking about how nice the weather is.

i’m in scottsdale, az now where hot is really hot. last year there were 55 days above 43°c and looks like we’re in for a new record. 200 heat related deaths so far and will break the record of 350+ last year.

as the song says

i gotta get outta this place

if it’s the last thing i ever do…

5 ( +5 / -0 )

as the song says

i gotta get outta this place

if it’s the last thing i ever do…

We gotta get outta this place, by The Animals, was a big hit among American soldiers in Vietnam. The title says it all (although it had nothing to do with the climate).

1 ( +1 / -0 )

Firstly, remove the stupid masks from your faces and chins. You will be a lot more comfortable in this humidity!!!

Agreed. The muppets also do themselves no favours going out in the heat of the day dressed in black clothing.

-1 ( +4 / -5 )

I'm just saying, anyone living within a twenty miles or so of the beach here on the west coast of the US doesn't have to worry about prolonged bouts of 40 degree C temperatures. At least not yet. Even here, every few decades, we will get a few days in a row when the high temps reach 44 C.

California is a large state. We have the highest mountain in the lower 48, Mt. Whitney, and not far away from there, the hottest place on the planet, Death Valley.

Sorry about the high temps and humidity in parts of Japan, but there are places with worse climate.

0 ( +2 / -2 )

There is a scenario which has not been talked about much, but which, if it came to pass, would drastically alter the climate on the west coast of North America, in a bad way.

There has been a lot of talk about what a collapse of the Gulf Stream current in the North Atlantic would do the climate of Europe. Most people who follow these discussions have heard that the melting of the Greenland ice sheet might cause a huge change in the weather patterns of Europe. Another consequence of a change in the world's ocean currents MIGHT be the weakening of the California Current along the coast, from British Columbia to the Baja peninsula.

The California Current brings cold water from the Arctic southwards. This current keeps temperatures generally cooler and humidity lower than they otherwise would be. If this ocean current sees a large change, which is certainly within the realm of possibility, the price of California real estate might go way down.

4 ( +5 / -1 )

It was 38 degrees in Nagoya today.

Pure hell.

0 ( +0 / -0 )

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