Ocean currents affect rainfall in the following ways
Affect Rainfall: The winds blowing over warm currents pick up and carry moisture and bring rainfall. For example, the North Atlantic Drift brings rainfall in some areas located along the western coasts of Europe. On the contrary, cold currents do not bring rainfall and make the region cooler and drier. The Kalahari Desert hardly experiences rainfall because of the cold Benguela Current.
Also, Read Movements of Ocean Waters