Water systems can affect climate and precipitation. Whether positive or negative it definitely does. Here are a few ways!
Large bodies of water: Oceans, seas, and large lakes affect the climate of an area. Water heats and cools more slowly than land. So during summer, coastal regions will stay cooler and in winter warmer. This creates a balance.
Moisture: If an area has more moist air, than it is most likely to rain there more often.
Hannah R.L. - Water Systems 