Do you know Tomb-sweeping Day? It is another appellation of Chinese Qingming Festival (清明节).
As one of 24 Solar Terms in China, Qingming festival (Tomb-sweeping Day) originates from the Spring and Autumn era. It occurs around April 5 (Gregorian calendar) every year, after which the rainfall has increased and the earth takes on a bright and new look. It is on this day the transformation from Yin to Yang is actualized.
You may wonder why Qingming festival is called Tomb-sweeping Day. Since ancient times, Chinese people have been used to sweeping tomb sites of relatives and loved ones on this day, paying respect to the dead, which has evolved into a traditional custom.
(Source: bjchinese.bjedu.cn)