It's autumn in the morning and cold at night.

It's autumn in the morning and chilly in the evening, which means that "beginning of autumn" brings the weather change first. Beginning of autumn is the first 13 of the 24 solar terms and the first solar term in autumn, which falls on August 7-9 of the Gregorian calendar every year. Beginning of autumn doesn't mean the hot weather is over. Beginning of autumn is still in the summer heat period, but the summer heat will not come out until the second solar term in autumn, and the weather 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. According to the calculation method of "dog days", the days of "beginning of autumn" are often in the middle of dog days, 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.

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 began to change, and everything gradually declined 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. There are also customs such as "pasting autumn fertilizer" and "biting autumn".