Precipitation affects climate in several ways. It helps regulate air and land temperature, it determines plant life in the area that contributes to the climate, and it contributes to the formation of wind.
To understand how precipitation affects climate, we must first understand what climate is. Climate is the long-term weather patterns of a geographic area. As Mark Twain put it, “Climate is what we expect; weather is what we get.” One of the biggest factors determining an area’s climate is temperature, and precipitation plays an important role in regulating the temperature of both land and air. Water heats up and cools down more slowly than land does, so on hot days, water cools the land and on cold days it warms the land. This creates a moderating effect so that areas with high precipitation and locations near bodies of water do not experience the temperature extremes that drier climates do.
You might think that climate determines plant life, but plant life also has an effect on climate, and plant life depends on precipitation. Precipitation encourages a varied and heavy plant population, which traps water in the land, causing it to heat and cool more slowly and moderating temperature extremes. Plants also serve as a windbreak, slowing the evaporation of water and helping to mitigate storms.
Perhaps most importantly, precipitation is related to the formation of wind. When water evaporates, the resultant warm, moist air rises and cools to form clouds and creates a pocket of low pressure. More air rushes into this pocket, creating wind. The water in the clouds falls as precipitation. So it is really the water cycle creating precipitation that drives the formation of wind, which you experience as a feature of climate.