What is the California Current?

Mary McMahon
Mary McMahon

The California Current is an ocean current in the North Pacific which runs along the West Coast of the United States, moving to the south until it hits Baja, at which point it starts to drift westward. This current is one among a series of boundary currents which move along the earth's continents. The California Current is an example of an eastern boundary current, because it is bordered by land in the east.

The California Current runs along the Pacific coast of North America.
The California Current runs along the Pacific coast of North America.

The current originates in the North Pacific, where the water is very cold. It is relatively shallow, carrying a load of cold water which stimulates upwelling as it passes along the coastline. As it gets into warmer southern waters, the cold water starts to sink to the bottom, allowing warm water to rise and generating a warm current which travels across the Pacific Ocean. This current links with a western boundary current which travels up the coast of Asia before looping around to North America again.

The foggy days of California are caused in part by the California Current.
The foggy days of California are caused in part by the California Current.

The series of interconnected currents which circles the North Pacific is known as the North Pacific Gyre. These currents play an important role in the circulation of the ocean, and in the economies along the coastlines they travel past. In California, for example, the California Current contributes to one of the most productive marine ecosystems in the world, with nutrient rich water and some astounding biological diversity. The southward flow of the current also explains why the waters off the coast of California are cooler than waters at similar latitudes on the America's Eastern Seaboard.

The famous foggy days of California are in part caused by the movements of the California Current, illustrating another way in which it impacts life on land. The currents in the North Pacific Gyre also determine where floating objects in the ocean end up over time, as they move along with this spiraling group of currents sort of like soap bubbles caught in the swirl of water around a drain.

It is important to note that there are other offshore currents in addition to the California Current, and sometimes they change direction. Immediately offshore, smaller currents and eddies push water around in a variety of directions. These currents are extensively studied by oceanographers and others with an interest in ocean currents, such as rescue services which want to be able to narrow down the potential location of a disabled ship, a swimmer in trouble, or the body of someone who has drowned.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


What does it have to do with weather?


@PinkLady4 - I think the reason why the California coastal waters don't get that warm is because the current keeps flowing south and the cold water current from the north keeps flowing south, as well.

So maybe because of the constant mixing of the cold and warmer water, the waters of the California Current have a huge variety of plant and sea animals. The waters are loaded with nutrients. It must be a great place to go scuba diving.


I'm curious to know just how cool the water is on the California coast compared to the coastal waters of Washington and Oregon. The ocean waters along the coast of Washington and Oregon are about 50 degrees most of the time. That's very cold!

If the cold water current sinks when it hits California and warmer water replaces it, you would think that the water would be warm enough to comfortably swim in. But maybe not.

It's interesting how ocean currents can affect the weather. Everyone has probably heard of the frequent fog in San Francisco. An even as far south as San Diego, under the right conditions, they can also have a lot of fog.


@bagley79 - Oh, that is so sad! I have always wanted to swim in the ocean off of California’s coast, and I envisioned it as being really warm and pleasant.

That’s probably because on television, people are always wearing bikinis on the beach, so we naturally assume the water must be as warm as it is in Florida. I can’t imagine how all the surfers bear the chilly water temperature! If there’s anything worse than being cold, it’s being cold and wet.


This must explain why the water in the Pacific Ocean in southern California feels so cold. I always thought that since they had such mild temperatures for most of the year, the water in the ocean off the coast would be warm as well.

The times that I have been able to swim in the ocean, the water has always been cold enough that I needed a wet suit.

My nephew who lives there, says that because of the California Current, the water is cold most days of the year. I guess if you wanted to be in the ocean bad enough, you would either get used to it or just plan on wearing a wet suit.

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