In the Gregorian calendar, the Start of Summer usually falls around May 5, and more often refers in particular to the day when the sun is exactly at the celestial longitude of 45°. As its name suggests, Start of Summer marks the beginning of summer, but is not actually consistent with the real start summer. According to climatology, summer starts only if there are five consecutive days with a temperature higher than 22 °C.
People in China normally followed several customs on this day, such as weighing oneself and eating eggs, in the hope of warding off the heat and preventing disease. For example, on this day people in Yangzhou Jiangsu Province often eat spiced boiled eggs with tea leaves or salted duck eggs.