How do ocean currents influence the climate of a place?

Warm currents along east coasts warm coastal areas in the mid latitudes while on the west coasts cool currents act as a cooling modifier as along the California coast. The warm Mid Atlantic Drift modifies what would have been an extremely cold climate in Iceland.

When currents happen little waves are being pushed toward the shore or away from the shore. When being pushed toward the shore cool air is being blown toward land making the air cooler. for exaple the air near a beach will be cooler at night because of ocean breeze