Japan Names Days Over 40C as 'Kokushobi'

Japan has a new name for very hot days. If the temperature is 40C or more, it is called 'kokushobi'. This name means 'cruelly hot'. Last summer was the hottest ever in Japan, with many days over 40C.

Japan has revealed a new term, 'kokushobi', for days when temperatures reach 40C (104F) or higher. This name, which translates to 'cruelly hot', was chosen after a national survey. Last summer was the hottest on record, with many extreme heat days, highlighting the impact of climate change.

In response to last year's unprecedented heat, Japan has introduced a new designation for days exceeding 40C (104F), termed 'kokushobi', which translates to 'cruelly hot'. This term emerged from a national survey conducted by the Japan Meteorological Agency, reflecting growing concerns over climate change and its effects on weather patterns. The summer of 2025 marked the hottest on record, with average temperatures significantly above normal and numerous days surpassing 40C, underscoring the urgency of addressing extreme weather events.