End of Heat

End of Heat (Chushu) is the fourteenth of the twenty-four solar terms and the second solar term of autumn, occurring annually between August 22 and 24 in the Gregorian calendar. “Chu” means “to cease” or “to terminate”; Chushu indicates that the scorching summer heat is coming to an end. However, due to a brief return of hot weather commonly known as the “autumn tiger,” sustained high temperatures and oppressive, muggy conditions can still persist after Chushu. The weather transitions from blazing hot to sultry and stifling; truly cool weather generally does not arrive until around the time of White Dew (Bailu). During Chushu, the Big Dipper points to the terrestrial branch wu (southwest), and the sun reaches the ecliptic longitude of 150°.

The term “Chushu” has a long history, already appearing in the Guoyu (Discourses of the States), where it clearly refers to changes in temperature. In the Western Han dynasty’s Huainanzi·Tianwen Xun (The Huainan Masters: An Explanation of the Celestial Patterns), “Chushu” was explicitly listed among the twenty-four solar terms. The Han dynasty text Xiaojing Wei (Apocrypha of the Classic of Filial Piety) records: “Fifteen days after Greater Heat, when the Dipper points to kun, it is Beginning of Autumn. ‘Autumn’ means ‘to gather and restrain’ — all things at this time gather and contract. Fifteen days later, when the Dipper points to shen, it is End of Heat, meaning that the lingering heat is about to withdraw, and yang qi lies hidden in concealment.” The Northern Song dynasty’s Taiping Yulan·Shixu Bu (Imperial Reader of the Taiping Era: Section on Seasonal Sequence) states: “On the day of End of Heat, the hawk sacrifices birds. Five days later, heaven and earth begin to turn austere. Another five days later, the grain ripens and is harvested; palaces and chambers are repaired; walls are mended.” The Yuan dynasty scholar Wu Cheng’s Yueling Qishier Hou Jijie (Collected Explanations of the Seventy-Two Pentads of the Monthly Ordinances) records: “End of Heat falls in the middle of the seventh month. ‘Chu’ means to stop — the summer heat reaches its end at this point.”

Before the End of Heat solar term, Heilongjiang and the northern parts of Xinjiang have already entered autumn, while North China and the Central Plains gradually follow suit toward the end or close of the Chushu period. After Chushu, the point of direct solar incidence continues to shift southward, solar radiation weakens, the subtropical high-pressure system retreats southward, and the Mongolian cold high-pressure system begins to influence China’s weather. Temperatures gradually decline. The rainy season in the northeast, North China, and the northwest is the first to end, ushering in the period of the year with the fewest rainy days and least cloud cover. Folk customs during Chushu are mostly related to welcoming autumn and celebrating the harvest. With crops in their critical ripening phase, farmers carry out rituals such as “lifting the fierce general to drive away locusts” and worshipping the Earth God. Fishing communities, who live by the sea, hold grand opening-of-the-fishing-season festivals. Additionally, the Zhongyuan (Ghost) Festival often falls during the Chushu period, making ancestor veneration and the floating of river lanterns significant festive activities at this time.