The Japan Meteorological Agency has introduced the term "kokushobi" to describe days when temperatures exceed 40°C [1].
This linguistic shift reflects the growing urgency of climate change in East Asia. By expanding its heat-classification system, Japan aims to better communicate the risks associated with increasingly frequent extreme-heat events [2].
The new word, which translates to "cruelly hot day," creates a specific category for temperatures that surpass the previous thresholds of the agency's monitoring system [1]. This addition allows meteorologists to provide more precise warnings to the public as summer peaks become more intense.
Officials said the decision to implement the new terminology was driven by the need to highlight the impacts of a warming planet [2]. The agency is updating its framework to ensure that the severity of these heatwaves is accurately captured in official records and public alerts.
While Japan has long used categories for hot days, the emergence of "kokushobi" marks a formal recognition that 40°C [1] is becoming a relevant benchmark for the region's weather patterns. The agency said the term serves as a tool for public safety and climate tracking [2].
“Japan has introduced the term "kokushobi" to describe days when temperatures exceed 40°C.”
The creation of a specific term for 40°C heat indicates that temperatures previously considered anomalous are now becoming frequent enough to require their own classification. This move suggests that Japan's public health and infrastructure strategies must now account for a new baseline of extreme heat that exceeds traditional summer norms.
