How do ocean currents affect precipitation?

Cold ocean currents are claimed to prevent clouds from forming, therefore lowering precipitation rates. Warm currents bring air masses, increasing humidity, which increases the number of clouds.
The graph below is of floods caused by rain in El Nino years vs. normal years.

How do ocean currents affect coastal climate?

Ocean currents usually flow from the poles or the tropics. Water flowing from the tropics flows to the poles and regulates the temperature when the cold and warm water collide, making sure the climate at the poles does not get too cold. It does this because when water is warm, it swells, stretching out to other colder climates. When the water becomes cold, the water contracts to the warmer regions. But there are exceptions, such as El Nino. This is caused when the Pacific current shifts, changing direction.

What makes ocean currents flow?

Many things make ocean currents flow; wind, gravitational pull (tides), the Coriolis effect, and the Sun. We'll be discussing wind because that is the theme of the entire blog. Wind can move surface water with friction, creating surface currents. Surface currents themselves can then evolve into a gyre. This is a spiral of water flowing on the ocean.