Chushu occurs at celestial longitude 150°, around August 22-24. The character "處" (chǔ) here means to depart — the lingering summer heat begins to step back. Cool air masses from the north start dominating.
Tradition: floating river lanterns (放河燈) for ancestors during Ghost Month; eating duck for nourishment. Climate: cooling becomes evident; harvest season begins for early autumn crops.
Everything turns on the word chǔ (處). In classical usage it carries the sense of halting or coming to rest, and the almanac tradition reads the term accordingly: the heat stops here. It does not mean “heat in this place.” Unlike Xiaoshu and Dashu, which grade the intensity of summer, Chushu (處暑 Chǔ Shǔ) names the closing of a process: a verb, not a measurement. Only a few of the twenty-four terms are built this way; Shuangjiang, Frost's Descent, is the other clear case in autumn. Taking chǔ at face value as “here” produces the exact opposite of the intended sense. Equating Chushu with the end of the dog days is the other slip; those are counted from geng-stem days after the summer solstice, so the final period closes on a date that drifts around Chushu from year to year — sometimes the same day, sometimes ten days apart, never by rule. A stretch of returning heat afterwards is normal and does not mean the term is inaccurate.
For chart work the node/mid-term distinction matters more than the name does. Chushu is a mid-term, so crossing it changes nothing in the pillars — the month branch remains Shen, set two weeks earlier at Liqiu. Mid-terms carry a different job in the calendar itself: the luni-solar year places its intercalary month by them, and a lunation containing no mid-term becomes a leap month. Chushu therefore has no direct effect on a Bazi chart while shaping the structure of the lunar calendar around it. It still has an indirect use. The Yuanhai Ziping and Sanming Tonghui traditions transmit tables of hidden-stem duty that divide each month by the days elapsed since the node — the Shen month splitting among Wu earth, Ren water and Geng metal, with Geng generally taking charge around Chushu. The day counts differ from one transmitted table to the next, with seven-, three- and ten-day versions all in circulation, so practitioners usually treat them as one reading among several and not as settled fact.
The three pentads recorded for Chushu are the hawk making an offering of birds, heaven and earth beginning to grow stern, and the grain coming in. The hawk hunting in quantity and laying out its catch was read as the first sign of autumn's severity; the second phase describes plants turning from growth to contraction; the third is the early rice harvest. That “severity” in classical usage describes a gathering-in and a settling of accounts — the basis of the old autumn assizes — and in chart reading it is not a synonym for misfortune.
Across Liqiu, Chushu and Bailu the summer leaves in three moves: a calendrical boundary, a turn in the heat, and finally dew on the grass confirming the cool. The branch changes do not keep step with them — Liqiu opens Shen, Chushu sits inside Shen, and only Bailu opens You. Keeping three lines apart — the season's name, the felt temperature, and which month pillar applies — resolves most of the confusion people have with the autumn terms.
It is read chǔ and means to halt or come to rest, so Chushu says the heat stops here. It is not saying “it is hot in this place,” which is the usual guess from the modern sense of the character. Only a few solar terms are named for an action rather than a degree; Chushu and Shuangjiang are the autumn examples, and in both the name records a turning point in a process.
No. Chushu is a mid-term, and only nodes open a month: Liqiu starts the Shen month, Bailu starts You, Hanlu starts Xu. Chushu falls inside the Shen month, so the pillar is Shen both before and after it. What mid-terms actually govern is intercalation in the luni-solar calendar — a lunation with no mid-term in it is designated a leap month.
No. The three periods of summer heat are counted from geng-stem days following the summer solstice, so the closing date shifts each year against the solar calendar. Chushu is fixed at 150° of celestial longitude, roughly 22–24 August. The two can coincide or fall ten days apart, and neither can stand in for the other.
A solar term describes the sun's position and the long-run average climate, not any particular day's weather. After Chushu the subtropical high often swings back for a spell, producing the returning heat known in Chinese as the autumn tiger, and the effect is strongest in the south. Traditional calendars use the term to fix months and farming schedules; meteorological definitions of autumn use a different test entirely.