The traditional East Asian calendars divide a year into 24 solar terms (節氣). Yǔshuǐ or Usui (Chinese and Japanese: 雨水; Korean: 우수; Vietnamese: Vũ thủy; literally: "rain water") is 2nd solar term. It begins when the Sun reaches the celestial longitude of 330° and ends when it reaches the longitude of 345°. It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 330°. In Gregorian calendar, it usually begins around 18 February (19 February East Asia time) and ends around 5 March.

Read more about Usui:  Pentads