2. The dog days appear in the summer heat and the summer heat, which is the day with the highest temperature, humidity and sultry weather in a year. The so-called dog days refer to the dog days of the lunar calendar, that is, the hottest period of the year. It can be understood that crouching means that the weather is too hot to move. But the dog days are called volts because there are also many cold factors. The dog days are the hottest 30 or 40 days in a year in the Central Plains. The dog days are calculated according to the lunar calendar, and they are between the middle and late July and the early August of the solar calendar.