Solar longitude
120°
Classification
Principal term · 气 qi
Month boundary
Does not open a month
Definition
What Major Heat marks
The season behind the name
Major Heat represents high summer in the traditional calendar, linking strong heat with tending growing crops.
These names grew from seasonal observation and farming practice. They describe a traditional seasonal sequence, not a weather forecast for every region.
Major Heat begins at the instant the Sun reaches 120 degrees of apparent ecliptic longitude. It is one of 24 equal 15-degree divisions of the solar year, so its Gregorian position changes only slightly from year to year.
As a qi term, Major Heat marks the alternating mid-month point in the solar-term sequence. It does not open a solar branch month, and it does not open a lunar month.
The time is shown in China Standard Time (UTC+8). A reader west or east of that zone may see the same instant fall on a different local civil date.
Three pentads · 三候
Seasonal observations
Each traditional pentad spans about five days and names a seasonal sign associated with that part of the term.
- First pentad
Decaying grass is said to become fireflies
腐草为萤
- Second pentad
The earth turns damp in sultry heat
土润溽暑
- Third pentad
Heavy rains fall in season
大雨行时