"Spring rain is as expensive as oil" usually occurs in which month?

For the northern part of China, which has been suffering from spring drought, and for the traditional agriculture that depends on the weather, spring rain is absolutely scarce, so there is a saying that it is "as expensive as oil".

In fact, the reason why the ancients named the first solar term after beginning of spring as "rain" is not only based on the experience summarized year after year, but also the factor of expecting rain: "Good rain knows the season, and it happens in spring. Sneak into the night with the wind and moisten things silently. " Since ancient times, people have had fixed seasonal and climatic judgments, corresponding farming activities and some special folk customs in the rain and solar terms.

Rain is the second of the 24 solar terms. Wu Cheng, a Yuan Dynasty man, said in the twenty-four solar terms: "It rains in the first month. Water falls from the sky, and beginning of spring belongs to wood. However, if it comes from wood, it will also come from water, so beginning of spring has succeeded in raining. If the east wind melts, it will disperse into rain. " It means that rain gives birth to everything, and spring is coming.