What are the unique characteristics of slight cold weather?

The average temperature during the slight cold in Beijing is generally around -5℃, and the extreme minimum temperature is below-15℃. At this time, the average temperature in Northeast China is around -30℃, the extreme minimum temperature can be as low as -50℃, and the average maximum temperature in the afternoon is only -20℃. The average temperature in the area north of 45 N in Heilongjiang, Inner Mongolia and Xinjiang and the northern part of Qinghai-Tibet Plateau is around -20℃, and the average temperature in the area near 40 N in the west of Hetao is around-10℃. The average temperature of the first line to Qinling Mountain is about 0℃, and there is no seasonal frozen soil in the south of the line, and there is no obvious wintering period for winter crops. The average temperature in the south of the Yangtze River is generally around 5℃. Although the field is still full of vitality, cold air sometimes goes south, causing certain harm.