Minor Cold小寒

Minor Cold (小寒, Xiǎo Hán) is the twenty-third of the twenty-four solar terms and, in the BaZi calendar, the term that opens the 丑 month. It is an astronomical instant, not a day: the moment the sun reaches 285° of ecliptic longitude, which falls on 5 or 6 January depending on the year.

Its name places it a rung below the term that follows it, Major Cold — but the naming is about position in the sequence, not a claim that one is milder than the other. Both sit deep in the coldest stretch of the northern-hemisphere year, at the point furthest in ecliptic terms from the warmth of Beginning of Spring.

Astronomically it sits between the Winter Solstice and Major Cold, still close to the sun's lowest arc of the year. In the agricultural calendar it traditionally marks a quiet stretch: little field work is possible, and the period is largely one of waiting out the cold on stores laid in months earlier.

Minor Cold is a 節 — a month-opening term — so at the instant the sun crosses 285° the month pillar's branch becomes 丑 (Chǒu). It is one of the twelve month-openers that structure the BaZi year, moving the month pillar only; the year pillar turns solely at Beginning of Spring, still a month away.

This site's engine confirms the mechanism directly. Scanning day by day, the month pillar steps into 丑 by 6 January 2026 — already showing in the reading taken at noon that day, since the precise instant of the term can fall a little earlier or later within the same date. A birth from this instant until Beginning of Spring reopens the cycle carries a 丑 month pillar because of this term.