JAPAN

JMA introduces new name for days of 40 C heat

Beginning this summer, the weather agency will refer to the hottest days as kokushobi, a description that translates as "severely hot day."

By The Japan Times

• April 17, 2026 at 5:18 AM

JMA introduces new name for days of 40 C heat Photo: The Japan Times

Japan on Friday adopted a new name for days with temperatures reaching 40 degrees Celsius or higher
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As human-caused climate change brings increasingly intense heat waves to Japan, days with temperatures reaching 40 degrees Celsius or higher have now earned a new name — kokushobi — courtesy of the Japan Meteorological Agency (JMA), which announced it on Friday.The term, which uses the Japanese kanji koku (酷) — meaning harsh or cruel — to describe the intensity of the heat, will enter the lexicon used by the JMA in weather forecasts starting this summer.The new description translates as “severely hot day.”
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