Video: Gyres (1:04)
As surface winds push the surface layer of the ocean with them, the surface wind gyres result in surface ocean current gyres. Along coastlines, the direction of movement of a gyre has a significant impact on continental climate. For example, a current moving from south to north in the northern hemisphere, or north to south in the southern hemisphere, will generally deliver warmer water to the coastal region, whereas a current moving from the north to south in the northern hemisphere or south to north in the southern hemisphere will generally deliver colder water. The flow of warm water will generally cause a larger moderating influence on coastal climate than will the flow of cold water. Take, for example, the Gulf Stream in the North Atlantic. This warm current has a major heating effect on the shores of Great Britain and other parts of Northern Europe, keeping these regions relatively balmy compared to locations at comparable latitudes. After it bathes the shores of Britain, the North Atlantic gyre bends towards the south, thus bringing relatively cold waters to the shores of Spain, Portugal, and Morocco further to the south, keeping these areas cooler than areas not influenced by the currents.
This NASA video provides an excellent summary of surface ocean currents: