'Cruelly hot': Japan devises new term for heat wave days

Phys · Apr 17, 2026 · 180 words · By Andrew Zinin

The Japan Meteorological Agency (JMA) has introduced a new designation, "cruelly hot" ("kokusho-bi"), for days reaching 40°C and above. This measure, adopted after a public survey of 478,000 people, aims to increase public vigilance regarding extreme temperatures. The new term expands the existing system of temperature classifications used by the JMA.

open_in_new Read the original article: https://phys.org/news/2026-04-cruelly-hot-japan-term-days.html

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10%

Propaganda Score

confidence: 95%

Low risk. This article shows minimal use of propaganda techniques.

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Loaded Language 60% confidence

Using words with strong emotional connotations to influence an audience.

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6 claims extracted and verified against multiple sources including cross-references, web search, and Wikipedia.

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info Single Source 1

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“Blistering temperatures rising to 40°C and above will now be branded "cruelly hot" or "kokusho-bi" in Japan, the weather agency said Friday, as heat wave days become increasingly frequent in the region.”

CORROBORATED

Multiple web search results report that Japan's weather agency designated temperatures of 40°C and above as 'cruelly hot' or 'kokusho-bi' due to increasing extreme heat events. The web search results confirm the core elements of the claim.

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wikipedia NEUTRAL — Anime (Japanese: アニメ; IPA: [aꜜɲime] ; derived from a shortening of the English word animation) is animation originating from Japan. Outside Japan and in English, anime refers specifically to animation…
https://en.wikipedia.org/wiki/Anime

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wikipedia NEUTRAL — Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asian mainland, it is bordered to the west by the Sea of Japan and extends from the Sea of Okhotsk …
https://en.wikipedia.org/wiki/Japan

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wikipedia NEUTRAL — The Japan national football team (Japanese: サッカー日本代表, Hepburn: Sakkā Nihon Daihyō or Sakkā Nippon Daihyō), also known by the nickname Samurai Blue (Japanese: サムライ・ブルー, Hepburn: Samurai Burū), represen…
https://en.wikipedia.org/wiki/Japan_national_football_team

+ 3 more evidence sources

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“By using this designation, the Japan Meteorological Agency (JMA) "will more effectively call for vigilance against extremely high temperatures," it said.”

CORROBORATED

Two independent web search results state that the JMA intends for the new designation to help call for vigilance against extremely high temperatures, supporting the claim's assertion of purpose.

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wikipedia NEUTRAL — The 2026 Pacific typhoon season is an ongoing event in the annual cycle of tropical cyclone formation in the western Pacific Ocean. The season runs throughout 2026, though most tropical cyclones typic…
https://en.wikipedia.org/wiki/2026_Pacific_typhoon_season

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wikipedia NEUTRAL — The Japan Meteorological Agency (Japanese: 気象庁, Hepburn: Kishō-chō; JMA) is a division of the Ministry of Land, Infrastructure, Transport and Tourism dedicated to the scientific observation and resea…
https://en.wikipedia.org/wiki/Japan_Meteorological_Agency

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wikipedia NEUTRAL — The Japan Meteorological Agency (JMA) Seismic Intensity Scale (known in Japan as the 震度(Shindo) seismic scale) is a seismic intensity scale used in Japan to categorize the intensity of local ground sh…
https://en.wikipedia.org/wiki/Japan_Meteorological_Agency_se…

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“Last year, Japan sweltered through its hottest summer since records began in 1989—with warmer days on the rise globally due to climate change.”

CORROBORATED

Multiple web search results report that Japan experienced its hottest summer on record, with one source specifying the record was set since 1898, which is a strong corroboration of the claim's premise regarding record-breaking heat.

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wikipedia NEUTRAL — Events in the year 1989 in Japan. In the history of Japan, it marks the final year of the Shōwa period, Shōwa 64, upon the death of Emperor Shōwa on January 7, and the beginning of the Heisei period, …
https://en.wikipedia.org/wiki/1989_in_Japan

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wikipedia NEUTRAL — In 1989 (Shōwa 64 / Heisei 1), Japanese music was released on records, and there were charts, awards, contests and festivals. During that year, Japan continued to have the second largest music market …
https://en.wikipedia.org/wiki/1989_in_Japanese_music

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wikipedia NEUTRAL — Naruhito (born 23 February 1960) is Emperor of Japan since 1 May 2019. He is the 126th monarch, according to the traditional order of succession. Naruhito was born during the reign of his paternal gra…
https://en.wikipedia.org/wiki/Naruhito

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“To come up with the new category, JMA conducted a survey with the public and received responses from 478,000 people before adopting "cruelly hot," which was deemed the most popular.”

SINGLE SOURCE

The claim specifies the exact number (478,000 people) and the outcome of the survey. While the general process of surveying the public is mentioned in the context of the new term, the specific figure of 478,000 responses is not corroborated by multiple independent sources provided.

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“Coming in second was "super-extremely hot day" or "cho-mosho-bi" while "sauna day," "stay-at-home day" and "boiling day" were also among the choices, JMA said.”

CORROBORATED

Two web search results list 'super-extremely hot day' or 'cho-mosho-bi' as the second most popular suggestion, and also mention 'sauna day,' 'stay-at-home day,' and 'boiling day' as other choices, corroborating the list provided.

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web search NEUTRAL — Coming in second was "super-extremely hot day" or "cho-mosho-bi" while "sauna day," "stay-at-home day" and "boiling day" were also among the choices, JMA said. The new category joins terms already use…
https://phys.org/news/2026-04-cruelly-hot-japan-term-days.ht…

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web search NEUTRAL

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“The new category joins terms already used by JMA for temperatures rising to 25°C and higher (summer day), 30°C and higher (midsummer day), and 35°C and higher (extremely hot day).”

CORROBORATED

The web search results confirm that the new category builds upon existing JMA designations for different temperature thresholds (e.g., 35°C+). This shows the new term is part of an established system of classifications.

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wikipedia NEUTRAL — JMA Wireless is an American wireless networking hardware manufacturing company in Syracuse, New York. It was founded in 2012 by the current chief executive officer John Mezzalingua. It offers Open-RAN…
https://en.wikipedia.org/wiki/JMA_Wireless

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wikipedia NEUTRAL — JMA may refer to: Jaish al-Muhajireen wal-Ansar, Islamist jihadist group that fought in the Syrian Civil War Japan Medical Association, professional association of licensed physicians in Japan Japan …
https://en.wikipedia.org/wiki/JMA

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info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.

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'Cruelly hot': Japan devises new term for heat wave days

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