When does the heat start? What is summer heat?

1, summer heat is also called dog days, and the beginning of summer heat is based on the theory that the summer solstice is the third Geng day after the summer solstice.

2, dog days, one volt is ten days, calculated by days. Therefore, the dog days are divided into three days, that is to say, after the third day of Gengtian, the summer solstice is the first day, the first volt. From the summer to the third watch in the future, the initial fall is 10 days, the middle fall is 10 days or 20 days, and the final fall is 10 days. In ancient China, the "trunk-branch calendar" was popular, and 60 groups of different names were used to record dates with 10 heavenly stems and 12 earthly branches, which were recycled. The day with the word "Geng" is called "Geng Day".