NOAA’s latest map of coastal water temperatures along the south Washington coast shows temperatures above 61F (16C) … see below. Cooler water is found along the Oregon and California coasts. Much warmer water is found offshore. At Ocean Shores or Long Beach, you can almost go into the water without a wetsuit.
How do these temperatures compare to normal? Below are anomalies (differences) from the climate (or normal) of sea surface temperatures. Warmer than usual by about 2-3 degrees Celsius along the coast and the warmth extends offshore. Cooler than usual along the California coast.
Before explaining why, I would like to mention that late August is the time when temperatures are generally warmest along our coast. To illustrate, here is a chart of sea surface climate temperatures in Ocean Shores, WA from the excellent website, Weatherspark. The typical peak ocean temperature on August 28 was 58 degrees Fahrenheit, compared with lower 60s temperatures today.
So why are the water temperatures warmer than usual this year? An important problem is that cold water flows from below the surface will be weaker.
And why is it weaker? Because the usual high pressure offshore has been weaker than usual over the past few months.
High pressure offshore leads to northerly winds (winds from the north) along our coastal regions. These winds blow over the ocean’s surface, and due to the planet’s rotation, this leads to offshore currents. To compensate for the loss of water, cool water flows up from below.
The high pressure off the coast…. is called the East Pacific High Temperature – related to northerly winds along the coast (see chart).
Over the past month, an area of unusually low pressure has been located off the coast of Oregon, something represented by the difference in pressure from normal over the past 30 days is found below. This results in weaker northerly winds, less cooling water coming up from below, and warmer than normal coastal temperatures.
Sea level difference from normal in the past month
