Why is the spring drought in North China more serious?

This should start with the source of precipitation in North China. China is an area where monsoon prevails. Winter winds blow from the northwest mainland, bringing little water vapor, making the air look very dry. Summer monsoon blows mostly from the southeast ocean, bringing a lot of water vapor, which is the main source of precipitation. Every year, the summer monsoon arrives in North China later than in Central China and South China, and leaves earlier than in Central China and South China. Generally speaking, the summer monsoon prevails in North China in July and August, which is also the rainy season of the year in North China. There is a lot of precipitation in the rainy season. For example, the average precipitation in July and August in Beijing accounts for 63% of the annual average precipitation. In spring, most of the time in North China is still controlled by relatively dry continental air, so it is difficult to form precipitation. But the weather in spring is not as stable as in winter, and there are many changes. During this period, there are many opportunities for low-pressure activities. Some of these depressions come from the far west, and some are produced in North China or Northwest China. When these low pressures pass by, it can cause precipitation and windy weather, and the precipitation in North China in spring is mainly supplied by this low pressure activity. However, because most of these depressions are moved from the arid areas in northwest China, there is little water vapor in the air, so the precipitation is still not much.