Cold Food Festival, held on April 4 if it is aleap year(China); and its related observances:

An ancient Chinese tradition where fire is avoided and cold dishes are eaten, observed on April 5 (or April 4 in leap years).
The Cold Food Festival dates back to the Spring and Autumn period and honors the loyal retainer Jie Zhitui. According to legend, his master Duke Wen of Jin declared a day of cold food to commemorate Jie’s loyalty. Families prepare cold rice cakes, vegetables, and other dishes the day before traversing ancestral tombs. This observance often precedes or coincides with the Qingming Tomb-Sweeping Festival. While fewer people now strictly avoid fire, many still enjoy the unique culinary custom. The day highlights themes of remembrance, respect for ancestors, and the endurance of cultural heritage.
Cold Food Festival leap year