The day pillar for Friday, 23 July 2027

Day pillar	癸卯 (gui mao)
Heavenly stem	癸 (gui)
Earthly branch	卯 (mao)
Day element	Water 水 (shui)
Polarity	Yin
Solar term	大暑 (dashu)
Month pillar	丁未 (ding wei), governed by 小暑 (xiaoshu)

Today's day pillar is 癸卯 (gui mao), a yin Water day in the sixty-day cycle. Today is also the solar term 大暑 (dashu), one of the twenty-four stations of the solar year. The month pillar is 丁未 (ding wei), governed by the term 小暑 (xiaoshu).

大暑 (dashu), major heat

大暑 is the hottest stretch of the year in the calendar's reckoning, around the twenty-third of July.

It is the greater half of the pair that began at 小暑 (xiaoshu). Traditionally it overlaps with the 三伏 (san fu) dog days, the hottest period of the Chinese summer, and a good deal of old advice about rest and food is attached to it.

大暑 is a medial term inside the 未 (wei) month, so no pillar changes. It is the last term of summer, and the season ends a fortnight later while the temperature is still at its highest.

That mismatch between the calendar and the thermometer is a feature. The terms are tracking the sun, and the ground takes weeks to catch up or cool down.