Major Snow大雪

Major Snow (大雪, Dà Xuě) is the twenty-first of the twenty-four solar terms and, in the BaZi calendar, the term that opens the 子 month — the Rat month, the pillar most closely watched in winter readings. It is an astronomical instant: the moment the sun reaches 255° of ecliptic longitude, which falls between 6 and 8 December depending on the year.

This is the term most worth getting right in English-language BaZi writing, because the common shorthand gets it backwards. It is Major Snow, not the Winter Solstice two weeks later, that opens the 子 month; by the time the solstice arrives, the month pillar has already been sitting on 子 for a fortnight.

Astronomically it sits between Minor Snow and the Winter Solstice, at the point in the northern hemisphere's year where snowfall — where the climate supports it at all — is at its heaviest and most sustained, escalating from the lighter snow named two terms earlier. In the agricultural calendar it traditionally marks deep winter dormancy: little field work is possible, and the stores laid in earlier in autumn are what matter now.

Major Snow is a 節 — a month-opening term — so at the instant the sun crosses 255° the month pillar's branch becomes 子 (Zǐ). It is one of the twelve month-openers that structure the BaZi year, moving the month pillar only.

This site's engine gives a precise reading for 2026: at 12-07 10:52 the sun crosses 255°, and the month pillar switches at that instant. Checking either side of it directly — 09:00 that morning the pillar is still 己亥, by 12:00 it is already 庚子 — shows the change landing exactly where the term predicts, not smeared across the day.

The Winter Solstice follows on 12-22 that same year, and the same engine check across that date shows the month pillar sitting on 庚子 both immediately before and immediately after it — no movement at all. The 子 month opened here, at Major Snow, and stays open through the solstice and beyond, until Minor Cold closes it a month later.

Winter Solstice (冬至) — The twenty-four solar terms. The pairing this site's engine data is built to correct: Winter Solstice is widely described in English-language sources as the point where the 子 month, or even the whole lunar year cycle, begins. It does not open anything — that happens here, at Major Snow, a full two weeks earlier.