San Juan Islands water temp
This data the coastal San Juan Islands ocean water temperature today, tomorrow and the upcoming days. Besides, you can also get information about the weather and surf forecast, as well as the data on sunrise / sunset and moonrise / moonset at a given point on any given day.
Current ocean temperature in San Juan Islands
Water temperature in San Juan Islands today is 54.7°F. Based on our historical data over a period of ten years, the warmest water in this day in San Juan Islands was recorded in 2017 and was 55.6°F, and the coldest was recorded in 2008 at 50.7°F. Sea water temperature in San Juan Islands is expected to drop to 52.7°F in the next 10 days. September average water temperature in San Juan Islands is 52.5°F, the minimum temperature is 49.6°F, and the maximum is 56.3°F.
Throughout the year, the water temperature in San Juan Islands does not rise above 68°F and therefore is not suitable for comfortable swimming. The average water temperature in San Juan Islands in winter reaches 46.2°F, in spring 47.7°F, in summer the average temperature rises to 52.7°F, and in autumn it is 50.5°F.
San Juan Islands water temperature now
| September 5, 2025 |
|---|
| today temp |
| 54.7°F |
| September 4, 2025 |
|---|
| yesterday temp |
| 55°F |
The ocean salinity in San Juan Islands is 27.82‰, and the average salinity of the World Ocean is 35‰.
Surf Forecast in San Juan Islands for today
Another important indicators for a comfortable holiday on the beach are the presence and height of the waves, as well as the speed and direction of the wind. Please find below data on the swell size for San Juan Islands. We calculate the swell size based on the mean wave height (trough to crest) of each third highest wave. For more information on surf forecasts for the next ten days, please visit sea state forecast San Juan Islands. Data in table shown for September 5, 2025, time in GMT 0 format (you can change the time zone on the sea state forecast page)
| 0-3 h | 3-6 h | 6-9 h | 9-12 h |
|---|---|---|---|
| 1' 1" | 1' 6" | 1' 4" | 0' 11" |
| 0.34 m | 0.46 m | 0.41 m | 0.27 m |
| 12-15 h | 15-18 h | 18-21 h | 21-24 h |
|---|---|---|---|
| 0' 7" | 0' 4" | 0' 2" | 0' 2" |
| 0.17 m | 0.11 m | 0.06 m | 0.04 m |
Surf report in San Juan Islands
San Juan Islands weather forecast
Current temperature and weather
Data in a table show San Juan Islands temperature today (September 5, 2025). For more information and forecast for a few days, go to the weather forecast San Juan Islands.
| 0-3 h | 3-6 h | 6-9 h | 9-12 h |
|---|---|---|---|
 |  | |  |
| 57.4°F | 56.3°F | 55.6°F | 56.3°F |
| 12-15 h | 15-18 h | 18-21 h | 21-24 h |
|---|---|---|---|
|  | | |
| 59.7°F | 63.3°F | 63.5°F | 60.8°F |
You may also be interested in other sections of our site for San Juan Islands: Sunrise and Sunset, Tides
San Juan Islands water temperature by month
These figures shows the average, minimum and maximum monthly sea temperature in San Juan Islands. In addition to the table values, the graph below displays of changes average surface temperature during the year. Values are calculated based on the data over the past 10 years. Using them, you can check the water temperature in San Juan Islands on any day of this period that interests you. Click on the month link and you will see a table for each day, or alternatively you can view the temperature curve of the month and select 2 different years you want to compare, either in a table or as a curve
Chart monthly average water temperature in San Juan Islands
