Average Ocean Temperatures for Washington State

Average ocean temperatures for northern Washington state are listed below for each month in degrees Fahrenheit and degrees Celsius.

The three sites with measurements are 1) Neah Bay at the northwest tip of the Olympic Peninsula, 2) Port Townsend on the northeast side of the Olympic Peninsula at the entrance to Puget Sound and 3) Seattle in the midst of Puget Sound.

Among these locations, the ocean at Seattle is generally the warmest, reaching an average of 56 °F (13 °C) from mid July until mid September. Neah Bay is more exposed than the other spots to the open Pacific, and has slightly cooler water in summer and fall. Yet in March, Neah Bay is where the warmest ocean can be found.

The coolest sea water of the year sits off Port Townsend in winter, where it averages 44 °F (7 °C) in January and February.

These coastal water temperatures are averages compiled by the National Oceanographic Data Center. Actual ocean temperatures do vary from year to year depending upon the weather and the flow of ocean currents.