According to scientists, during the Autumn Equinox season, the daily average temperature over the vast area of the Yangtze River and area to its north, drops to 22℃ below zero. At this point, cold air from the north gains some power. The rainy season in most areas of China is over. Descriptions such as cool breeze, blue sky, the sunny fragrance of Osmanthus blossoms, fat crabs, yellow chrysanthemums are all part of this period. According to the Chinese lunar calendar, the fall begins on the first day of "Start of Autumn" and ends at "frost descent". The Autumn Equinox occurs exactly at the midpoint of the 90 days from the first day of Start of Autumn to the beginning of Frost Descent.

From the Autumn Equinox Day, the climate has three main characteristics:

1. The location of direct sunlight keeps moving from the equator to the southern hemisphere. The days in the Northern Hemisphere get shorter and nights get longer, this phenomenon being more and more obvious until the Winter Solstice, when the day is the shortest and the night is the longest.

2. There is a gradual increase in the temperature difference between day and night, and the range will be higher than 10℃;

3. Temperatures drop day by day, and gradually the late autumn season comes. The situation in the Southern Hemisphere goes through the opposite changes.

Autumn Equinox is an important solar term for agricultural production. After that, the temperature decreases significantly. An old farming proverb says: "It gets colder and colder after the cold autumn showers, one after another." Sometimes in the Northeast region of China, the appearance of frost during the Autumn Equinox is not surprising.

In autumn, temperatures drop fast, making autumn harvest, autumn plowing and autumn planting extraordinarily tense. The Autumn Equinox is a good time to harvest. Cotton is in full boll opening, and tobacco leaves turn from green to yellow. In North China, people start planting winter wheat, while along the Yangtze River and in the vast region of the South to Yangtze River people are busy harvesting rice and plowing the land to cast their rapeseeds.

Drought or incessant rain during Autumn Equinox season can negatively affect the above activities. Rain, especially, makes the crops lay flat, rotten, musty or germ-infested, resulting in serious losses.