Beginning of autumn doesn't mean the extreme hot weather is over. It is still very hot in early autumn. The so-called "heat is in the dog days" is also called "beginning of autumn drops later", and there is at least "falling" hot weather after beginning of autumn. "Three Volts" can be divided into initial volt, intermediate volt and final volt, and its date is determined by the matching of solar term date and main branch year date. According to the calculation method of "three volts", the day of "beginning of autumn" is often still in the midsummer period, that is to say, the heat is not over, and the real coolness usually comes after the Millennium solar terms. The watershed of summer heat is not in the solar terms in beginning of autumn.
Autumn is a season of alternating hot and cold. "Guanzi" said: "Autumn begins in the shade, so everything is harvested." After entering autumn, the climate changed from rainy and humid in summer to dry and rainy in autumn. In nature, the qi of Yin and Yang begins to change, Yang gradually recedes, Yin gradually forms, and everything gradually declines with the sinking of Yang. The most obvious change in autumn is that the leaves of vegetation change from lush green to yellow, and the leaves begin to fall and the crops begin to mature. Beginning of autumn is one of the "four seasons and eight festivals" in ancient times. People have the custom of offering sacrifices to the land gods and celebrating the harvest.