Source: JPL Horizons On-Line Ephemeris System

The traditional East Asian calendars divide a year into 24 solar terms (节气). Dàshǔ (pīnyīn), Taisho (rōmaji), or Daeseo (romaja) (Chinese and Japanese: 大暑;Korean: 대서;Vietnamese:Đại thử;literally: "major heat") is the 12th solar term. It begins when the Sun reaches the celestial longitude of 120° and ends when it reaches the longitude of 135°. It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 120°. In the Gregorian calendar, it usually begins around 22 July (23 July East Asia time) and ends around 7 August.