TL;DR: Sương Giáng (霜降) is the 18th of the 24 solar terms and the last term of autumn, beginning when the Sun reaches 210 degrees of ecliptic longitude. In 2026 it begins at 16:39 on 23 October, Vietnam time; from 2020 to 2051 it falls on 23 October every year. It is the mid-month term of the ninth lunar month, so it does not change the Bát Tự month pillar. The Hiệp kỷ biện phương thư lists its three pentads: the dhole lays out its prey as an offering, grass and trees yellow and shed leaves, hibernating insects lie still. In Vietnam, Sương Giáng is not a major festival; it falls in the ninth lunar month, the month in which the Gia lễ giản yếu sets the new-rice Tết.
What is Sương Giáng (Frost's Descent)?
Sương Giáng is the 18th of the 24 solar terms (counting from Lập Xuân), falling after Hàn Lộ and before Lập Đông, and it is the last term of autumn. The name 霜降 means "frost descends", referring to the time when the air is cold enough for moisture to settle as frost on grass and trees. The term begins when the Sun reaches 210 degrees of ecliptic longitude.
Sương Giáng is a mid-month term (trung khí), not a term that opens a month. The Hiệp kỷ biện phương thư records "寒露九月節" and "霜降九月中", that is, Hàn Lộ opens the ninth month and Sương Giáng is the mid-month term of the ninth month[1]. The book also distinguishes "月建視節氣斗杓也月將視中氣太陽也": the month branch (nguyệt kiến, set by the handle of the Big Dipper) follows the opening terms, while the monthly general (nguyệt tướng, set by the Sun) follows the mid-month terms[1]. So in Bát Tự, a person born before or after the Sương Giáng transition still belongs to the Tuất month; the month pillar only changes to Hợi at Lập Đông.
When does Sương Giáng begin?
In 2026, Sương Giáng begins at 16:39 on 23 October, Vietnam time (UTC+7), which is the 14th day of the ninth lunar month. The transition time falls nearly 6 hours later each year, then moves back a day in a leap year, so the Gregorian date varies between 22 and 24 October: from 1900 to 2100, 113 years fall on the 23rd, 72 years on the 24th (the last in 2019) and 16 years on the 22nd (starting in 2052); from 2020 to 2051 it falls on 23 October every year.
| Year | Gregorian date | Transition time (UTC+7) |
|---|---|---|
| 2025 | 23 Oct | 10:53 |
| 2026 | 23 Oct | 16:39 |
| 2027 | 23 Oct | 22:26 |
| 2028 | 23 Oct | 04:15 |
| 2029 | 23 Oct | 10:03 |
| 2030 | 23 Oct | 15:52 |
Calendars printed in China time (UTC+8) can show a date one day later than Vietnamese calendars. In 2023, Sương Giáng began at 23:19 on 23 October Vietnam time, which was already 00:19 on 24 October Beijing time.
The Hiệp kỷ biện phương thư records "霜降日躔卯宮初度是為大火之次": at Sương Giáng the Sun enters the first degree of the Mão palace, called the Đại Hỏa station among the twelve stations of ancient astronomy[1].
Is Sương Giáng a holiday or a Tết?
Sương Giáng is not a major festival in Vietnamese culture but a late-autumn solar-term marker. Under the old two-crop pattern, main-season (vụ mùa) rice was transplanted in the fifth and sixth lunar months and harvested in the eighth and ninth, so Sương Giáng falls in the main-season harvest.
The Gia lễ giản yếu by Dương Bá Trạc (1932) keeps only three Tết for offerings to the ancestors: the Lunar New Year, Thanh Minh and "the new-rice Tết (any day in the ninth month will do)"[2]. The book does not tie the new-rice Tết to the solar-term day.
Because Sương Giáng is the mid-month term of the ninth month, from 1900 to 2100 its transition day always falls in the ninth lunar month, except in 2033, when it falls on the first day of the tenth month.
What are the three pentads of Sương Giáng in the old books?
Each solar term is divided into three pentads (hậu) of about five days each. In its section on pentads (氣候), the Hiệp kỷ biện phương thư records the three pentads of Sương Giáng as:
- First pentad (sơ hậu): 豺乃祭獸 (sài nãi tế thú), the dhole lays out the animals it has caught as if making an offering.
- Middle pentad (trung hậu): 草木黄落 (thảo mộc hoàng lạc), grass and trees turn yellow and shed their leaves.
- Last pentad (mạt hậu): 蟄蟲咸俯 (trập trùng hàm phủ), hibernating insects all bow down and lie still[1].
Table of the 24 solar terms and the position of Sương Giáng
To see where Sương Giáng sits in the system, compare the table below. The solar terms are grouped by season, six per season, and Sương Giáng is the sixth, that is, the last term of autumn:
| Season | Term 1 | Term 2 | Term 3 | Term 4 | Term 5 | Term 6 |
|---|---|---|---|---|---|---|
| Spring | Lập Xuân | Vũ Thủy | Kinh Trập | Xuân Phân | Thanh Minh | Cốc Vũ |
| Summer | Lập Hạ | Tiểu Mãn | Mang Chủng | Hạ Chí | Tiểu Thử | Đại Thử |
| Autumn | Lập Thu | Xử Thử | Bạch Lộ | Thu Phân | Hàn Lộ | Sương Giáng |
| Winter | Lập Đông | Tiểu Tuyết | Đại Tuyết | Đông Chí | Tiểu Hàn | Đại Hàn |
This table matches the mnemonic verse of the 24 solar terms: "Xuân vũ kinh xuân thanh cốc thiên / Hạ mãn mang hạ thử tương liên / Thu xử lộ thu hàn sương giáng / Đông tuyết tuyết đông tiểu đại hàn". The third line lists the six autumn terms, with Sương Giáng last.
Sương Giáng in the divination arts
In the East Asian divination arts, solar terms in general and Sương Giáng in particular serve as markers for calculation. The Trạch vận tân án records date ranges within the Hàn Lộ and Sương Giáng terms when discussing the annual and monthly stars[3]. This uses the solar term as a unit of time in phong thủy trạch vận, not as a claim about human destiny.
In Kỳ Môn Độn Giáp, the Kỳ Môn Chỉ Quy discusses calculating siêu thần, tiếp khí and trí nhuận from the solar terms: "kì môn chuyên trọng tiết khí", meaning this art places special weight on solar-term markers[4]. In Lục Nhâm, the monthly general changes at the mid-month term: the Hiệp kỷ biện phương thư writes "霜降九月中日躔在卯宫為九月將", so from Sương Giáng the monthly general of the ninth month is in the Mão palace[1]. The Đại Lục Nhâm bí bản calls the Mão palace Thái Xung (太冲) and places the Phòng and Tâm lunar mansions in it, in its table "二十八宿周天度位"[5]. The use of solar terms in these arts is a convention of each school, not a fact of natural science.
Nhật Nguyệt's suggestions for readers
Nhật Nguyệt's suggestion: to know exactly when Sương Giáng begins in a given year, look up the transition time in Vietnam time (UTC+7), not only the date. That moment does not change the Bát Tự month pillar, but it is when the Lục Nhâm monthly general moves to the Mão palace. Families holding the new-rice offering can choose any day in the ninth lunar month; it need not be the solar-term day.
Why is Sương Giáng often confused with Lập Đông?
Sương Giáng and Lập Đông are only about 15 days apart, and both are tied to the turn from autumn to winter. Many people take Sương Giáng as the "start of winter", while in fact Lập Đông is the term that opens winter in the solar-term calendar. Sương Giáng still belongs to autumn and is its last term. The Hiệp kỷ biện phương thư records Sương Giáng as the mid-month term of the ninth month ("霜降九月中") and Lập Đông as the term opening the tenth month ("立冬十月節")[1].
Is there a late-autumn grave-tending custom tied to Sương Giáng?
Grave tending is not a custom of the Sương Giáng term. The Gia lễ giản yếu places grave tending at the Thanh Minh Tết, "any clear dry day in the third month is fine for tending the graves", while the new-rice Tết in the ninth month is a day of offerings to the ancestors, with no mention of visiting graves[2].
