extremely hot day (≥35°C)
Colloquial term for a day when the maximum temperature reaches 35°C or higher. Compare with 猛暑日, which is the official JMA term for the same threshold.
See also: 猛暑日
extremely hot day (≥40°C)
Used by some agencies for days when the maximum temperature reaches 40°C or higher. This usage is less common and not standardized across all meteorological organizations.
Today is expected to be an extremely hot day (≥35°C), so heatstroke precautions are necessary.
Some agencies define a day with a maximum temperature exceeding 40°C as a 酷暑日.
Day with a maximum temperature of 30°C or higher. Less extreme than 酷暑日.
Night when the minimum temperature stays at 25°C or higher. Focuses on nighttime heat, unlike 酷暑日 which is about daytime maximums.
Compound of 酷暑 (intense heat) and 日 (day). The term likely emerged as an extension of existing temperature-based day classifications like 真夏日 and 猛暑日.