This summer my family and I visited both the East Coast and the West Coast, dipping our toes in the Atlantic and Pacific Oceans. This gave us first-hand experience with just how chilly Pacific waters are.

When we visited the Delaware shore in late June, the water was around 70^oF. Then, in late July, we headed west and spent some time at the beaches just north of San Diego. Now, San Diego is at about the same latitude as Charleston, South Carolina, yet the ocean water off San Diego was only around 65^oF, colder than the waters off Delaware were a month earlier. The reason for this lies in the direction of offshore ocean currents.

Off the East Coast, the prevailing current is the Gulf Stream, which flows northward moving relatively warm water. But off the West Coast, the dominant current is the California current, which flows southward from the chilly Gulf of Alaska. That's why waters off Delaware and New Jersey are generally warmer than those about 400 miles farther south off southern California, where surfers routinely don wet suits every time they hit the water.