Cold dew is a solar term that reflects the characteristics of climate change. After cold Dew, the days get shorter, the nights get longer, the sunshine decreases, the hot air slowly recedes, the cold air gradually grows, the temperature difference between day and night is larger, and the morning and evening feel a little chilly. After the cold dew, the cold air in the north has a certain force, and most parts of China are under the control of cold high pressure, and the rainy season is over. The weather is usually warm in the day and cool in the night, with clear skies. From the point of view of climate characteristics, during the cold dew season, the autumn sense in the south is getting stronger, the air is cool and the wind is cool, less rain and dry; The northeast and northwest regions of the north have presented winter scenes, thousands of miles of frost, thousands of miles of snow floating, and the southern autumn color is very different.

As the direct point of the sun continues to move southward in the southern hemisphere, the Angle of sunlight in the northern Hemisphere begins to tilt significantly, the solar heat received by the ground is significantly reduced than in the summer, and the influence of the cold air can sometimes extend to southern China. During the cold dew season, there is more dew and lower temperature. At the same time, temperatures continued to drop across much of southern China. The average daily temperature in South China is less than 20 ° C, and even in the areas along the Yangtze River, the temperature is difficult to rise above 30 ° C, while the lowest temperature can drop below 10 ° C. Except for a few valley lowlands in the Northwest Plateau, the average temperature of the pentad (5 days) is generally lower than 10℃, and it is already winter according to the standard of "pentad average temperature" to divide the four seasons.

Suitable for cold dew view of red leaves is the northern region, especially north of the Yellow River. The period for viewing red leaves in Beijing is from mid-October to early November, with the best period being from October 15 to 30. It can be said that Xiangshan is the most popular place to appreciate red leaves in China. When it comes to red leaves, people will unconsciously think and mention it. To appreciate the red leaves in Fragrant Hills during the cold dew season has long become the traditional habit of Beijing citizens and the highlight of autumn travel.