The ocean currents influence the climate of a place to a great degree and can dramatically alter the temperature regime of the areas concerned.
There are many ocean currents around the globe but the most famous are the following.
The Californian Current
This current flows past the coastline of San Francisco and Los Angeles and keeps the weather of the two cities very comfortable; especially of the latter station. The interesting thing is that it flows as a cool current in summer and as a warm current during winter. Therefore, when the continent America is freezing with several degrees below zero, the Californian coast rarely records temperatures below 40 F.
In summers, it the other way round. Almost all stations on continent US on the same parallel as San Francisco, record temperatures in excess of 100 F, whereas at San Francisco, it rare for the Mid-day thermometer to exceed even 90 F!; thanks to the cooling effect of the ocean current. In fact the California coast climate is so moderate due to this current that the coast is called land of perpetual spring. Few area in the world can compete the beauty of this climate.
The North Atlantic Drift
It is perhaps the most famous and most studied ocean current in the world and is responsible for keeping the coasts of UK up to Norway much warmer in winter than the continent Europe. To give a comparison, the places as far south as Madrid in Spain experience chilly winters and nowhere on the Central European Plain is temperature more than 25 F. Whereas the North Atlantic Drift keeps the English coasts relatively warm and its effect can be felt as far north as Oslo in Norway where Atlantic ocean rarely freezes and commercial activity continues.
The Labrador Current
It is the ‘Titanic Fame’ ocean current that was responsible for the Ship’s sinking in 1912. It is an icy cold ocean current. It is so cold that it causes icebergs to float at much lower latitudes than normal. The air above becomes extremely chilly and everything feels freezing. This current flows off the North East coast of Canada towards Europe and causes much problems to water traffic even now in this age of scientific advancement.
In short, the ocean currents cause huge anomalies in air temperatures over the areas which they affect. Consequently climate of the affected areas are highly dependent on them.