Lasting until the 8th August which is the begninning of Autumn

coinciding with the Celtic festival of Lammas the first harvest

https://en.wikipedia.org/wiki/Chinese_calendar

At Dashu, the sun crosses the celestial longitude of 120°, a full 30° past the summer solstice. While daylight hours have already begun to shorten after Xiaoshu (小暑), the cumulative heat from prolonged solar exposure and the Earth’s thermal lag push temperatures to their annual maximum. This term falls exactly in the middle of the 未 month in the BaZi calendar, which spans from Xiaoshu (approx. Jul 6-8) to the start of Liqiu (立秋, approx. Aug 7-9). Dashu does not trigger a month-pillar change—that occurs on the first day of 未 month (Xiaoshu) and next at Liqiu. Instead, Dashu marks the deepest internal stability of the Yin Earth (阴土) branch, a period when Fire is fully hidden, not expressed.

The ancient phenological text *《月令七十二候》* divides Dashu into three pentads (候): 1. Decaying grass turns into fireflies (腐草为萤) – The ancients believed fireflies emerged from rotting vegetation, symbolizing the transformation of death into light under extreme humidity. 2. Soil is moist and the air is hot (土润溽暑) – The earth becomes drenched with frequent thunderstorms, and moisture-laden air makes everything sticky. 3. Heavy rains fall in abundance (大雨时行) – Frequent downpours cool the land briefly, preparing it for the autumn harvest.