TL;DR: Điều hậu is the principle of balancing heat and cold in a Bát Tự chart: a winter chart that is too cold is said to need Fire, a summer chart that is too hot to need Water. The Cùng Thông Bảo Giám discusses each stem month by month, for example winter Đinh Fire should "use only Canh and Giáp"; the Trích Thiên Tủy sets the general rule of avoiding excess. This is a convention of the art, not verified, and the whole four pillars must be read, not just the birth season.
What is điều hậu in Bát Tự?
Điều hậu (調候, climate adjustment) is the principle of balancing hot and cold in a Bát Tự chart: besides weighing the strength of the five phases, the reader asks whether the chart leans too far toward cold or heat, and which stems and branches would bring it into balance. It is one axis of reading, alongside strength, structure and mediation.
Điều hậu is a convention of the art, rooted in Chinese destiny texts such as the Cùng Thông Bảo Giám and the Trích Thiên Tủy. It has not been verified as a scientific law.
Why are winter and summer the first two extremes discussed?
Winter and summer are the clearest ends of the hot-cold axis. In Bát Tự the birth month is set by the solar terms, not by the ordinary lunar month: those born in the Hợi, Tý and Sửu months belong to winter, those in Tỵ, Ngọ and Mùi to summer. The boundaries of those months are the Start of Winter, Start of Summer and the terms between them, which can be computed and cross-checked.
A chart that is too cold is said to need warming, one that is too hot to need cooling. These two extremes show the idea of điều hậu most clearly.
What does the Cùng Thông Bảo Giám say about winter?
The Cùng Thông Bảo Giám (窮通寶鑑), traditionally attributed to the editor Dư Xuân Đài, discusses each heavenly stem month by month. For winter it stresses the need for Fire to warm the chart, with different methods depending on the Day Master.
On Đinh Fire in the three winter months, the book says: "三冬丁火微寒，耑用庚甲" (Đinh Fire in the three winter months is slightly cold; use only Canh and Giáp)[1]: winter Đinh Fire is weak and needs Giáp Wood as fuel, with Canh Metal splitting the Giáp to lead the fire. The book also says "甲庚两透，科甲分明" (when Giáp and Canh both appear, examination success is clear)[1], an old way of using examination honours to describe a stem-branch structure regarded as favourable.
What does the book teach for summer and late summer?
For summer the focus is easing the heat: the book often calls for Water to moisten and Metal to produce Water. When the Fire qi has receded, the method changes: on Đinh Fire in the seventh month, the book says "七月丁火，退气柔弱，端用甲木" (Đinh Fire in the seventh month has receding qi and is soft and weak; use Giáp Wood)[5].
Điều hậu does not depend on the birth month alone. A summer chart with much Water in its four pillars needs little cooling; a winter chart with much Fire needs little warming.
How does the Trích Thiên Tủy ground điều hậu?
The Trích Thiên Tủy says: "天道有寒暖，发育万物，人道行之，不可过也" (The way of Heaven has cold and warmth to nourish all things; the way of humans follows it and must not go to excess)[3]. The point is to avoid excess, not that heat is bad or cold good.
The original note explains: "阴支为寒，阳支为暖；西北为寒，东南为暖；金水为寒，木火为暖" (yin branches are cold, yang branches warm; northwest is cold, southeast warm; Metal and Water are cold, Wood and Fire warm), and that cold qi blossoms when it meets warmth while warm qi matures when it meets cold[4]. Rèn Tiěqiáo (Nhậm Thiết Tiều), commenting on the book, wrote "命贵中和，偏枯终于有损" (a destiny values balance; one-sidedness ends in loss)[2]. Điều hậu is thus part of the principle of balance.
How can you tell whether a chart leans cold or hot?
Following the original note to the Trích Thiên Tủy and the Cùng Thông Bảo Giám's readings, the judgement rests on the stems and branches as a whole:
| Factor | Leaning cold | Leaning hot |
|---|---|---|
| Day stem | Nhâm, Quý (Water) | Bính, Đinh (Fire) |
| Month branch | Hợi, Tý, Sửu | Tỵ, Ngọ, Mùi |
| Phases in the four pillars | Much Metal and Water | Much Wood and Fire |
| Direction of the branches | Northwest | Southeast |
| Supporting stems and branches | No Fire to warm | No Water to moisten |
The table is a frame of reference, not a scoring formula; the books all require looking at the hidden stems within the branches before concluding.
Do the schools agree on điều hậu?
Not entirely. Some readers put điều hậu first, holding that if a chart is too lopsided in heat or cold other factors can hardly work; others treat it as one part, to be combined with structure and strength. The Cùng Thông Bảo Giám goes stem by stem and month by month; the Trích Thiên Tủy states the general principle of balance.
Nhật Nguyệt's suggestion: how to read điều hậu sensibly?
When reading a chart yourself, go in order: fix the birth month by the solar terms, count Metal and Water against Wood and Fire in the four pillars, and only then compare with the Cùng Thông Bảo Giám passage on your own day stem and birth month.
Điều hậu only describes the stem-branch structure under the art's conventions. Do not use it to decide on study, work or health.
