A si month bazi birth places you in the Snake month (巳 Sì), the fourth month of the Ba Zi (八字 bāzì) year and the start of summer. In Ba Zi the month pillar (月柱 yuèzhù) is the season pillar, and it is the single strongest factor in whether your Day Master (日主 rìzhǔ) reads strong or weak. The Snake month is where the year’s Fire begins to build in earnest.
The Snake month opens at the solar term Li Xia (立夏 Lìxià), around 5 May, not on any calendar date. Ba Zi months turn on solar terms (节气 jiéqì), so an early-May birth may still belong to the Dragon month. If your birth sits near the edge, confirm the exact solar-term moment with the free chart calculator before counting the pillar by hand.
Your si month bazi pillar by year stem
The month stem follows from your year stem by the Five Tigers rule (五虎遁 wǔhǔ dùn). Read your year stem on the left and take the Snake-month pillar.
| Year stem | Snake month pillar |
|---|---|
| 甲 Jiǎ | 己巳 Jǐ Sì |
| 乙 Yǐ | 辛巳 Xīn Sì |
| 丙 Bǐng | 癸巳 Guǐ Sì |
| 丁 Dīng | 乙巳 Yǐ Sì |
| 戊 Wù | 丁巳 Dīng Sì |
| 己 Jǐ | 己巳 Jǐ Sì |
| 庚 Gēng | 辛巳 Xīn Sì |
| 辛 Xīn | 癸巳 Guǐ Sì |
| 壬 Rén | 乙巳 Yǐ Sì |
| 癸 Guǐ | 丁巳 Dīng Sì |
Only five distinct pillars appear because year stems pair under the rule: 甲/己, 乙/庚, 丙/辛, 丁/壬, 戊/癸 share columns. The stem walks forward one place each month from the Tiger’s opening, so by the Snake — the fourth month — it has moved three steps. All five full columns are gathered in the master month stem table.
What the Snake month does to a chart
Si is the first month of summer, so Fire is prosperous and climbing toward its peak. The Snake branch is more layered than it looks: alongside its strong Fire it holds a seed of Metal, because early summer is where Metal is born and begins its long growth. This gives every Day Master a distinct reading. A Fire Day Master born here is strong and rising. An Earth Day Master is fed generously by the Fire and reads well. A Metal Day Master is technically out of season yet has a hidden root to build on, so it is not as helpless as high summer would make it. Wood is drained as it feeds the Fire, and Water is dried and pressured by the heat.
A point worth holding onto: the Snake is where Fire and the seed of Metal sit in the same branch, so it can quietly support two elements that normally oppose each other, which is why Snake-month charts often read less one-sided than the heat alone suggests. If your Day Master is Bing or Ding Fire, read this alongside Bing Fire born in summer for the fuller picture. For any other stem, the month is only the opening temperature; the final call on strong versus weak Day Master still rests on all four pillars.
The five states as summer opens (旺相休囚死)
The five states (旺相休囚死 wàng xiàng xiū qiú sǐ) are how classical texts score each element against the ruling season. The Snake opens summer: Summer = Fire season, branches 巳午未, May 5 – Aug 6 (from Li Xia 立夏 to before Li Qiu 立秋).
| Element | State | Reading in a Snake month |
|---|---|---|
| Fire | 旺 wàng — Prosperous | The season is your own element: maximum native strength; the chart usually needs outlets, not more support |
| Earth | 相 xiàng — Supported | The season feeds your element: strong by backing; comfortable, resourced, sometimes over-sheltered |
| Wood | 休 xiū — Resting | Your element feeds the season: energy flows out; mild drain, the retired-general state |
| Water | 囚 qiú — Confined | Your element controls the season: fighting uphill against the times; effortful, gritty |
| Metal | 死 sǐ — Dormant | The season controls your element: weakest baseline; support and timing matter more than effort |
Note the honest tension for Metal: the seasonal grid marks it Dormant, yet the Snake branch itself carries Metal’s birth. Both are true — the season presses Metal down while the branch quietly offers it a root — and a careful reading holds the two together rather than picking one.
What sits inside the branch
The Snake branch hides Bing Fire as its main charge, with Geng Metal at its point of birth and a trace of Wu Earth. The verbatim listing, first stem = main qi (本气 běnqì): Sì 巳 (Snake): Bǐng 丙 (Yang Fire), Wù 戊 (Yang Earth), Gēng 庚 (Yang Metal). That hidden Metal is what makes Si matter to Metal Day Masters. See the Si branch hidden stems for how the three are weighted.
Finding your Snake-month pillar
Any birth between Li Xia (~5 May) and Mang Zhong (芒种 Mángzhòng, ~6 June) carries 巳 in the month branch. Cross-check the stem: a 乙 year must show 辛巳, and the whole 乙 column can be verified in the Yi-year month stem table. Two checks matter most here — that early-May births have actually crossed Li Xia, and that the year stem you use is the Ba Zi year’s stem, fixed at Li Chun in February rather than at New Year.
The month palace
As the palace of career climate and of parents, a Snake-month pillar often points to a bright, quick, visible early environment: expressive and warm, with things heating up fast. Read it as the weather your working life began in, not a settled verdict. It carries the rising Fire that the Horse month will bring to full peak, and it stands opposite the deep-winter Pig month in the cycle of the year.
Snake month FAQ
Does the Snake month clash with anything?
Yes — in the fixed Six Clashes (六冲 liùchōng) list, 巳↔亥 oppose each other. A 亥 elsewhere in your chart clashes into the month palace, which we read as turbulence around career climate or the parental line, always judged against the whole chart.
Is a Water Day Master in trouble here?
The season marks Water Confined — controlling Fire is uphill work in its own season — so the baseline is effortful. But a Water Day Master with strong Metal resource and wet-earth roots elsewhere can still be judged strong. Baseline, not verdict.
I was born on 3 May. Snake month or Dragon month?
Almost certainly the Dragon, since Li Xia falls around 5 May, but the exact hour of the term shifts year to year. Plot the chart and let the true boundary decide before you read either pillar.
To see how your si month bazi pillar tilts your own Day Master strength, plot your full chart free with the Butcher Boy calculator.