Qi Men Dun Jia in the Southern Hemisphere: Solar Terms and Directions for Australia & NZ

Three Questions from Down Under

July in Melbourne is mid-winter, yet the Chinese calendar calls it “Minor Heat / Major Heat.” So southern-hemisphere practitioners ask three things: should the solar terms be reversed? Should the Yin/Yang cycles be swapped? Do the direction readings still hold?

Question 1: Reverse the Solar Terms? — Mainstream Answer: No

The “solar terms” used by Qi Men and BaZi are markers of the sun’s position on the ecliptic (Winter Solstice = the sun reaching 270° celestial longitude). They are astronomical events that occur at the same instant worldwide — there is no northern or southern version.

The mainstream traditional school (and virtually every charting tool): one global set of solar terms and Yin/Yang cycle rules. The Stem-Branch calendar records celestial mechanics, not local perceived temperature.
A minority reformist school: argues the seasons are flipped and the Yin/Yang cycles should be swapped south of the equator. An interesting position, but without classical textual basis or large-scale verification.

Qimena follows the mainstream: one global calendar. If your lineage teaches the reformist convention, be aware of the difference.

Question 2: How Are Directions Read? — By the Absolute Compass

“The auspicious sector is Southeast” means the absolute compass direction — unchanged by hemisphere: Sydney’s southeast is wherever the compass says southeast is.

One perceptual trap: in the southern hemisphere the midday sun sits in the north. If you habitually estimate direction by the sun (“sun side = south”), it inverts down under — trust your phone’s compass instead.

Question 3: True Solar Time? — Applies as Usual, Two Notes

The True Solar Time formula is global (full explanation). For southern users:

Enter longitude normally: Sydney at 151.2°E is 151.2, Auckland at 174.8°E is 174.8 (positive east values; latitude does not affect the time math);
DST straddles the new year: south-eastern Australian states observe DST from the first Sunday of October to the first Sunday of April — apply the rollback when manually converting birth times (details); Queensland, WA and NT observe none.

Southern City Longitudes

City	Longitude	City	Longitude
Sydney	151.21	Perth	115.86
Melbourne	144.96	Auckland	174.76
Brisbane	153.03	Wellington	174.78

In Practice

For a present-moment chart: open the charting tool, tap GPS (Sydney is also in the city presets) and let the engine handle the rest. For natal charts: recover standard time using that year’s DST rule first, then correct for longitude. And if you follow the reformist solar-term school, tell the AI mentor your convention in the chat — it can discuss the chart within your framework.