It is because it needs a lot of water when it enters the milk ripening stage from the turning green stage, and at the same time, it needs enough water from sowing to emergence to make it grow normally. The spring drought in North China is more serious. Spring rain accounts for 10%- 15% of the annual precipitation, and in some places it is less than 10%. If it rains in time, it will naturally be particularly precious, so there is a saying that "spring rain is as expensive as oil".

Spring is followed by autumn and winter. If there is little rainfall in autumn and winter, the soil moisture itself is not good, and it is often easy to form drought in winter and spring.

The spring drought in North China is more serious. The spring rain accounts for 10- 15% of the annual precipitation, and in some places it is less than 10%. If there is little rainfall in autumn and winter, the temperature rises rapidly in spring, windy days and strong evaporation, it is often easy to form drought in autumn, winter and spring.

At the same time, it is the time when the overwintering crops turn green to milk maturity, which requires a lot of water supply, such as corn and cotton. It also needs plenty of water, so the spring drought is more prominent. If there is rain at this time, it will naturally be particularly precious, so there is a saying that "spring rain is as expensive as oil".

The climate in South China is different from that in South China. The weather turns warmer in early summer, and the rainfall in these areas increases due to the interaction between warm and humid air and cold air. People often say that "it rains in the Qingming Festival". Around April every year, the pre-flood season appears in all parts of South China, and then the rain belt advances from south to north. So there are more spring rains in the south.