Climate change is forcing governments to redefine their vocabulary. As summers shatter historical records year after year, the Japan Meteorological Agency (JMA) has taken an unprecedented step: the official creation of a new category for days exceeding 40°C (104°F), naming them “Kokusho-bi”—literally translated as “Cruelly Hot Day.”
A New Scale for a New Reality
Until recently, the highest alert level in the country was Mousho-bi (Extremely Hot Day), applied when temperatures reached 35°C (95°F). However, with cities now frequently hitting marks near 42°C, officials realized the existing terminology failed to convey the life-threatening nature of the current heatwaves.
Japan’s Updated Thermal Classification:
Summer Day: 25°C (77°F) or higher.
Midsummer Day: 30°C (86°F) or higher.
Extremely Hot Day (Mousho-bi): 35°C (95°F) or higher.
Cruelly Hot Day (Kokusho-bi): 40°C (104°F) or higher.
The Voice of the People: Why “Cruel”?
The choice of name was not arbitrary. The JMA conducted a massive public survey involving nearly half a million citizens. The term “Cruel” emerged as the winner over options like “Boiling Day” or “Sauna Day” because it effectively communicates a sense of urgency and immediate physical threat.
“The goal is for the population, especially the most vulnerable, to understand that a ‘Cruelly Hot Day’ is not fit for outdoor activities,” meteorological authorities stated.
Public Health Impact and Prevention
This semantic shift is accompanied by a reinforcement of emergency protocols. In Japan, heatstroke is a leading cause of hospitalization during the summer months. With the introduction of this new alert level, the government plans to:
1. Activate climate shelters in major urban centers.
2. Issue strict recommendations for air conditioning use, regardless of energy costs.
3. Suspend outdoor activities, including student sports and high-risk labor, during peak hours.
The creation of “Kokusho-bi” serves as a stark reminder that global warming is not just a statistic; it is a reality transforming how we live and communicate. Japan continues to lead the way in climate adaptation, prioritizing precise information to save lives in an increasingly warming world.
