Climate change is having an unforeseen consequence language – the creation new words. The Japan Meteorological Agency (JMA) has introduced a new item vocabulary the Japanese lexicon. The neologism is the word "kokushobi," which literally means "cruelly hot day" or "harshly hot day". The JMA will use it when describing or forecasting days when temperatures are 40ºC or . The JMA conducted an online poll weather-based terminology. The questionnaire was prompted the scorching weather experienced in Japan recent years. Website visitors selected their most preferred word. There were 478,000 responses. The word kokushobi garnered nearly 203,000 votes.
There has been record-breaking heat Japan in the past decade. The JMA reported days 40ºC or above every year since 2018. In August 2025, the town Isesaki, Gunma Prefecture, recorded the highest temperature ever observed Japan. The mercury rose to 41.8ºC. There were a further nine days when temperatures were 40ºC. More records were broken 2025. This was the hottest year since records began 1898. Temperatures were 2.36ºC average. The Mainichi newspaper wrote: "Tokyo recorded 25 days 35ºC, compared an annual average of just 4.5 days. Kyoto logged 52 days above that temperature, compared an average 18.5 days."
