What is the difference between the weather before Qingming Festival and the weather after Qingming Festival?

Qingming Festival, also called the Outing Festival, according to the Gregorian calendar, it falls between April 4th and 6th every year. It is the time when the spring scenery is bright and the grass is green, and it is also the time when people go out for spring outings. It is a good time for outing (called outing in ancient times), so the ancients had the custom of outing during Qingming Festival and carrying out a series of sports activities. Qingming Festival was also called March Festival in ancient times and has a history of more than 2,000 years. Qingming Festival falls around April 5th in the Gregorian calendar and is one of the twenty-four solar terms. Among the twenty-four solar terms, only Qingming is both a solar term and a festival.

Although it heralds warmer weather and bright flowers and green willows, it is also often "bad weather". As far back as the Liang Dynasty, someone recorded that during the Cold Food Festival two days before Qingming, there were often "strong winds and even rain". If it rains on the Qingming day, it is called "fire rain", which is also the "Qingming rain". Xiao Du (Du Mu and Li Shangyin are both called "Xiao Li Du") wrote about such a day.

The statistics of modern data analyzed the number of precipitations on Qingming Festival in some provincial capital cities from 1951 to 1980 and 1981 to 2010. It was found that after the reform and opening up, it rained less frequently during Qingming Festival. Moreover, the south generally experiences more precipitation than the north. Especially in the Jiangnan region represented by Changsha and Nanchang, it rained more than 30 times during the Qingming Festival from 1951 to 2010, which means that it rained on more than half of the Qingming Festivals.

From the perspective of solar terms, the Qingming solar term begins around April 5 and ends around April 20, which is mid-to-early April. Judging from the distribution of rainfall days in mid-to-early April, it is indeed proved that the Jiangnan area loves rain most during the Qingming solar term. This characteristic can also be reflected in the precipitation data along the middle and lower reaches of the Yangtze River and in more cities in the south of the Yangtze River.

However, since the 21st century, there have been more Qingming rains. Especially in Beijing, the number of rainfalls during Qingming Festival from 2001 to 2010 has been as much as that of Hangzhou, Nanjing, and Wuhan. Especially after 2010, the number of rainy days during Qingming Festival seems to be increasing across the country. During the Qingming Festival from 2011 to 2014, Qingming rain occurred not only in the south but also in many areas in the north.