How to say "precipitation" in Japanese

• 降水こうすいJLPT N1approx.Common
  nounCovers precipitation in the meteorological sense — rain, snow, and so on falling from the sky. This is the usual word for the weather phenomenon itself, as in forecasts and climate discussion.
• 沈降ちんこうCommon
  noun, suru verb, intransitive verbThis is a chemistry and medicine word for particles settling out of suspension, such as sedimentation of red blood cells; it is seldom what you want for rain or snow. Use it only for that settling sense.
• 降水量こうすいりょうCommon
  nounRefers specifically to the amount of precipitation, as measured or reported for a period or place. Choose this when discussing figures, measurements, or totals rather than the phenomenon itself.
  今夏こんかの降水量こうすいりょうは普通ふつうでなかった。↗

  This summer we had an unusual amount of rain.

For weather use 降水 or, when emphasizing the measured amount, 降水量; 沈降 is a different phenomenon entirely, covering settling or sedimentation rather than falling rain or snow.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 降水こうすいrainfall
• 沈降ちんこうsedimentation (e.g. of red blood cells)
• 降水量こうすいりょうamount of precipitation
• 沈殿ちんでんprecipitation
• 析出せきしゅつseparation