Autumn Equinox (Qiufen 秋分): dates, pentads and meaning
The Sun is overhead at the equator again, day and night are nearly equal, and autumn is split in half.
Autumn Equinox dates, 2026–2035
| Year | Date | Time (Taiwan, UTC+8) | Month pillar |
|---|---|---|---|
| 2026 | September 23 | 08:05 | still Ding-You 丁酉 month |
| 2027 | September 23 | 14:01 | still Ji-You 己酉 month |
| 2028 | September 22 | 19:45 | still Xin-You 辛酉 month |
| 2029 | September 23 | 01:38 | still Gui-You 癸酉 month |
| 2030 | September 23 | 07:26 | still Yi-You 乙酉 month |
| 2031 | September 23 | 13:15 | still Ding-You 丁酉 month |
| 2032 | September 22 | 19:10 | still Ji-You 己酉 month |
| 2033 | September 23 | 00:51 | still Xin-You 辛酉 month |
| 2034 | September 23 | 06:39 | still Gui-You 癸酉 month |
| 2035 | September 23 | 12:38 | still Yi-You 乙酉 month |
Times computed by our calendar code (UTC+8); they agree with an astronomical calculation to within about a minute. Between 1901 and 2100, Autumn Equinox always falls on September 22–24. Subtract 8 hours for UTC.
The three pentads of Autumn Equinox
| Sign of the season | When | |
|---|---|---|
| First pentad | Thunder falls silent (雷始收聲) | about days 1–5 after Autumn Equinox |
| Second pentad | Insects seal their burrows (蟄蟲坯戶) | about days 6–10 after Autumn Equinox |
| Third pentad | Waters begin to dry up (水始涸) | about days 11–15 after Autumn Equinox |
The ancients split each solar term into three pentads (hou 候) of about five days each, and marked them by changes in birds, animals and plants: seventy-two pentads a year. These follow the standard list in Wu Cheng's Yuan-dynasty Collected Explanations of the Seventy-Two Pentads. They were observed in the Yellow River basin, so they do not always match what you see in Taiwan, let alone elsewhere. Some, like hawks turning into doves, record old beliefs rather than biology.
Autumn Equinox in the sky: where the Sun is
The solar terms follow the Sun along the ecliptic: one term for every 15°, and Autumn Equinox is the moment the Sun reaches longitude 180°. In 2027, at Autumn Equinox the Sun sits against the stars of Virgo (drowned out by daylight, of course). That day in Taipei the Sun rises at 05:42 and sets at 17:49, about 12 h 7 min of daylight. Daylight is slightly longer than 12 hours because atmospheric refraction lifts the Sun into view early and keeps it visible late, and sunrise and sunset are timed by the Sun's upper edge.
What Autumn Equinox means in BaZi
Autumn Equinox is a qi (氣), or "middle term" (中氣): it falls in the middle of the You month (酉), so the BaZi month pillar does not change here; it is the same You month before and after. Middle terms matter in the calendar for another reason: a lunar month with no middle term in it becomes the leap month.
BaZi months are not counted from the lunar new moon but from the jie terms: Start of Spring, Awakening of Insects, Pure Brightness, Start of Summer, Grain in Ear, Minor Heat, Start of Autumn, White Dew, Cold Dew, Start of Winter, Major Snow and Minor Cold each open a month. If you were born on the day of a jie term, within a few hours of it, your month pillar (and for the Start of Spring, your year pillar too) can shift by one; it depends on the exact time. See solar term boundaries, and for how the month's heavenly stem is worked out, the month pillar.
Look up the solar terms for any year
Pick a year to list the exact time of all 24 solar terms (Taiwan time, UTC+8) and the month pillar each jie term starts. Add a month and day, such as a birthday, to see which solar-term period it falls in and its month pillar. Everything is calculated in your browser.
The times come from the same calendar code our BaZi charts use; for 1901–2100 they agree with an astronomical calculation to within about a minute. If you were born within minutes of a term changing, see solar term boundaries.
The terms before and after
The previous term is White Dew; the next is Cold Dew.
A straight word: solar terms are astronomy; luck is something else
The twenty-four solar terms divide the year by the Sun's position on the ecliptic, and their times can be computed to the second. BaZi uses them to change the year and the month; that is a rule of calculation. A solar term carries no good or bad luck of its own, and no term is a "better" one to be born in: a chart is read as a whole, by its Five Elements and Ten Gods. Everything on this site is for reference and entertainment.
Solar terms set the month; the month sets strength
Enter your birth date for a free Four Pillars chart and see your month element and the balance of your whole chart.
Autumn Equinox: common questions
What date is Autumn Equinox in 2026?
In 2026, Autumn Equinox falls on September 23 at 08:05 Taiwan time (UTC+8); in 2027 it is September 23 at 14:01.
Why does Autumn Equinox move from year to year?
A solar term is the moment the Sun reaches a set longitude, here 180°. A year is about 365.24 days, not a whole number, and leap years reset the count, so the date drifts within a few days. From 1901 to 2100, Autumn Equinox always falls on September 22–24.
What are the three pentads of Autumn Equinox?
First: Thunder falls silent (雷始收聲); second: Insects seal their burrows (蟄蟲坯戶); third: Waters begin to dry up (水始涸). They follow the standard Yuan-dynasty list.
What does Autumn Equinox do in a BaZi chart?
It is the middle term of the You month, so the month pillar does not change. BaZi changes months only at the jie terms.