1.
day when the maximum temperature stays below 0°C
A weather-service term for a day on which the highest temperature of the day does not rise above zero degrees Celsius. Such days are common in Hokkaido and mountain areas during midwinter and appear regularly in winter weather reports.
According to the forecast, tomorrow is expected to be the first day of this winter when the high stays below freezing.
Composed of 真 (true, truly) + 冬 (winter) + 日 (day). Literally "a true winter day." A technical term from the Japan Meteorological Agency, defined as a day whose maximum temperature does not exceed 0°C. The same set of terms defines various types of hot and cold days — see below.
TEMPERATURE DAY TERMS (Japan Meteorological Agency):
- 冬日: winter day — minimum temperature below 0°C (a frosty night, but the day may warm up)
- 真冬日: midwinter day — maximum temperature below 0°C (stays frozen all day)
- 夏日: summer day — maximum temperature at or above 25°C
- 真夏日: midsummer day — maximum temperature at or above 30°C
- 猛暑日: extremely hot day — maximum temperature at or above 35°C
- 熱帯夜: tropical night — minimum temperature at or above 25°C
Common collocations
- 真冬日が続く: days with highs below freezing continue
- 真冬日を観測する: to record/observe a sub-freezing day
- 今年初めての真冬日: the first sub-freezing day of this year
- 真冬日日数: the number of sub-freezing days
Usage
The word appears mainly in weather forecasts, news reports, and climate statistics. Because the definition is precise (maximum below 0°C), it has none of the vague feel of English "freezing day" — a 真冬日 is something that can be counted and tallied by weather stations. In Hokkaido, reports often highlight the number of consecutive 真冬日 during cold snaps.