The traditional chinese calendar divides a year into 24 solar terms.
[1] Yǔshuǐ / 雨水, Usui, Usu, or Vũ thủy, literally meaning rain water, is the second solar term.
It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 330°.
In the gregorian calendar, it usually begins around 18 February (19 February of / in east Asia time) and ends around 5 March.
Each solar term can be divided into three pentads (候), first (初候), second (次候) and last (末候) ones.