Xiazhi

The traditional Chinese calendar divides a year into 24 solar terms. Xiàzhì, "Geshi", "Haji", or "Hạ chí" is the 10th solar term, and marks the summer solstice. It begins when the Sun reaches the celestial longitude of 90° and ends when it reaches the longitude of 105°. It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 90°.
Western correlation.
In the Gregorian calendar, it usually begins around 21 June and ends around 7 July.
The solstices.
The solstices (as well as the equinoxes) mark the middle of the seasons in traditional East Asian calendars. Here, the Chinese character 至 means "extreme", which implies "solstices", so the term for the summer solstice directly signifies the summit of summer.