Japan reveals new name for 40C-and-hotter days after blistering summer

BBC News · 🇬🇧 public United Kingdom · Apr 17, 2026 · 286 words · By Mallory Moench

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What to know about Japan reveals new name for 40C-and-hotter days after blistering summer

Japan reveals new name for 40C-and-hotter days after blistering summer Japan has unveiled a new name for days that reach 40C (104F) or above, after the country experienced its hottest summer on record last year.

Claims checked 11

Techniques found 0

Topics 0

Coverage spectrum

Coverage gap: Low Left coverage

Left0%

Center80%

Right20%

5 sources compared across this story cluster. This is an eFinder estimate from indexed source coverage, not an editorial rating.

What happened

Why it matters

The term - kokushobi - has been translated as "cruelly hot", "brutally hot" or "severely hot" day by Japanese and international media.

Common ground

The name emerged as the most popular in a national online survey, with "super extremely hot day" in second place.

Perspective signals

No major persuasion pattern has been attached yet, so the source, headline, and evidence should carry most of the weight for readers.

Follow-up questions

What concrete event or decision sits underneath the headline: Japan reveals new name for 40C-and-hotter days after blistering summer?
What evidence would most clearly confirm or weaken the claim that Japan already has terms for days over 25C, 30C and 35C?
What should readers watch for in the next update to know whether the story is changing?

open_in_new Read the original article: https://www.bbc.com/news/articles/crr185nx0n9o?at_medium=RSS&at_campaign=rss

fact_checkClaims Checked

eFinder analyzed this article and checked 11 claims against available evidence, cross-references, web search, and Wikipedia. Here is what the fact-checking layer found.

info Single Source 4

check_circle Corroborated 4

help Insufficient Evidence 2

schedule Pending 1

info

Claim 1: “Japan already has terms for days over 25C, 30C and 35C.”

SINGLE SOURCE

The provided evidence for this claim consists of general Wikipedia and Britannica entries about Japan's geography and government, which do not mention meteorological terminology.

travel_explore

web search NEUTRAL — Japan is a constitutional monarchy with a bicameral legislature known as the National Diet. Widely considered a great power and the only Asian member of the G7, it maintains one of the world's stronge…
https://en.wikipedia.org/wiki/Japan

travel_explore

web search NEUTRAL — The official site of Japan National Tourism Organization is your ultimate Japan guide with tourist information for Tokyo, Kyoto, Osaka, Hiroshima, Hokkaido and other top Japan holiday destinations.
https://www.japan.travel/en/

travel_explore

web search NEUTRAL — 2 days ago · Japan is an island country lying off the east coast of Asia. It consists of a string of islands in a northeast-southwest arc that stretches for approximately 1,500 miles (2,400 km) throug…
https://www.britannica.com/place/Japan

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Claim 2: “The name emerged as the most popular in a national online survey, with "super extremely hot day" in second place.”

CORROBORATED

Multiple sources confirm 'kokushobi' won a national online survey and 'super extremely hot day' (chōmōshobi) came in second.

travel_explore

web search NEUTRAL — The term - kokushobi - has been translated as "cruelly hot", "brutally hot" or "severely hot" day by Japanese and international media. The name emerged as the most popular in a national online survey,…
https://www.bbc.com/news/articles/crr185nx0n9o

travel_explore

web search NEUTRAL — ‘Kokushobi’ translates as cruelly hot, brutally hot or severely hot. The name won a public vote, with ‘chōmōshobi’, meaning super extremely hot day, coming in second place.
https://www.euronews.com/2026/04/20/japan-announces-new-name…

travel_explore

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.
https://phys.org/news/2026-04-cruelly-hot-japan-term-days.ht…

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Claim 3: “The description, introduced by Japan's Meteorological Agency (JMA) on Friday, uses koku - meaning harsh or cruel - to describe the heat”

CORROBORATED

Web results confirm the Japan Meteorological Agency (JMA) introduced the term and that 'koku' refers to the harsh/cruel nature of the heat.

travel_explore

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Claim 4: “Japan has unveiled a new name for days that reach 40C (104F) or above”

CORROBORATED

Multiple independent web search results confirm that Japan has introduced a new term ('kokushobi') for days reaching 40C or above.

travel_explore

schedule

Claim 5: “Kyoto logged 52 days above the same temperature, compared with an average of 18.5 days.”

PENDING

This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.

info

Claim 6: “Temperatures reached 40C-plus on nine days between June and August, with a new national peak of 41.8C in the city of Isesaki.”

SINGLE SOURCE

The search results for this claim are dictionary definitions of the word 'between' and an app description, providing no meteorological data for Isesaki.

travel_explore

web search NEUTRAL — May 8, 2026 · Between has been used of more than two items since Old English; it is especially appropriate to signify a one-to-one relationship, regardless of the number of items.
https://www.merriam-webster.com/dictionary/between

travel_explore

web search NEUTRAL — Between provides free and clear Voice Calls. Keep on talking without the worry of phone call charges. Do you remember the day you first met, your first anniversary, or a special trip together? These s…
https://between.us/

travel_explore

web search NEUTRAL — 3 days ago · It is sometimes said that between usually applies to two things, while among applies to more than two things. According to the Oxford English Dictionary: "In all senses, between has been,…
https://en.wiktionary.org/wiki/between

info

Claim 7: “The survey was conducted in February and March and received roughly 478,000 responses, in which people picked their preferred term among 13 options to describe the hottest day.”

SINGLE SOURCE

While the general event is corroborated, the specific details about the survey (February/March, 478,000 responses, 13 options) are mentioned in the search results but not independently verified by multiple distinct reporting bodies in the provided snippets; however, one source explicitly mentions the 478 thousand people.

travel_explore

web search NEUTRAL — Use Microsoft Forms to easily create online surveys, forms, quizzes and questionnaires. AI powered, free survey tool from Microsoft.
https://forms.microsoft.com/

travel_explore

web search NEUTRAL — Build and design a survey or form in no time with AI, start from scratch or use one of our 500+ templates.
https://www.surveymonkey.com/

travel_explore

web search NEUTRAL — Easily create forms and surveys to gather data and gain insights from anywhere. Select from multiple question types, organize them with a drag-and-drop interface, quickly customize each to fit...
https://workspace.google.com/products/forms/

help

Claim 8: “The cumulative number of extremely hot days also surpassed the previous record set in 2024.”

INSUFFICIENT EVIDENCE

No evidence was found after searching.

help

Claim 9: “Tokyo recorded 25 days over 35C, compared with an average of just 4.5 days.”

INSUFFICIENT EVIDENCE

No evidence was found after searching.

info

Claim 10: “Summer 2025 was the hottest since records began in 1898 - with average temperatures nationwide 2.36C above average.”

SINGLE SOURCE

The search results for this claim are generic definitions of 'summer' or local camp/festival ads and provide no data on 2025 temperature records.

travel_explore

web search NEUTRAL — Summer or summertime is the hottest and brightest of the four temperate seasons, occurring after spring and before autumn. At or centred on the summer solstice, daylight hours are the longest and dark…
https://en.wikipedia.org/wiki/Summer

travel_explore

web search NEUTRAL — The Summer Day Camp Program's mission is to provide high-quality and engaging youth programs that nurture social skills, kindle new interests, and promote physical activity.
https://www.medfordoregon.gov/Government/Departments/Parks-R…

travel_explore

web search NEUTRAL — Boasting 79 years of family fun with a parade, festival market, evening street dance and more. You’ll enjoy live music and performing arts, classic cars and farm equipment, sports and tournaments, art…
https://www.whattodoinsouthernoregon.com/summer-festivals

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Claim 11: “The term - kokushobi - has been translated as "cruelly hot", "brutally hot" or "severely hot" day by Japanese and international media.”

CORROBORATED

Three independent sources confirm the translation of 'kokushobi' as 'cruelly hot', 'brutally hot', or 'severely hot'.

travel_explore

web search NEUTRAL — The term - kokushobi - has been translated as "cruelly hot", "brutally hot" or "severely hot" day by Japanese and international media.
https://www.bbc.com/news/articles/crr185nx0n9o

travel_explore

web search NEUTRAL — Following the hottest summer on record, the Japanese have a new term for days that reach 40°C or above – kokushobi which means cruelly, brutally or severely hot. Japan's Meteorological Agency (JMA) wi…
https://www.yourweather.co.uk/news/science/kokushobi-japan-s…

travel_explore

web search NEUTRAL — Japanese and foreign media translate the term "kokushobi" as "cruelly hot", "brutally hot" or "extremely hot" day. The naming came from a nationwide online survey involving some 478 thousand people.
https://statement.com/1193409/japan-introduces-new-name-for-…

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.