Sea TemperaturesSan Juan Islands Sea Temperature
Looking to find out what the sea water temperature in San Juan Islands is for today and the next few days? Below are data and charts that will give you information about sea temperatures in San Juan Islands and nearby locations.
Water temperature in San Juan Islands right now
Below is the current sea temperature for San Juan Islands, United States on January 10, 2026.
Today
7.62° C
45.72° F
Yesterday
7.6° C
45.68° F
A week ago
7.77° C
45.99° F
This water is very cold and can cause pain. We don't recommend you swim in this temperature for anything other than very short swims of 5 to 10 minutes unless you are a very experienced cold water swimmer.
The average sea temperature for San Juan Islands on January 10 over the last 10 years is 7.62° C (45.72° F), with a low temperature of 6.91° C (44.44° F) and a high of 8.44° C (47.19° F).
Analysis and forecast for San Juan Islands water temperatures
The water temperature in San Juan Islands today is the same as the average temperature of 7.62° C (45.72° F) and the temperature on this day last year was 7.62° C (45.72° F).
The chart and table below shows the change in water temperature in San Juan Islands over the last 30 days:
| Date | Temperature (Celsius) | Temperature (Fahrenheit) |
|---|---|---|
| January 10 | 7.62° C | 45.72° F |
| January 9 | 7.6° C | 45.68° F |
| January 8 | 7.72° C | 45.89° F |
| January 7 | 7.77° C | 45.98° F |
| January 6 | 7.78° C | 46.01° F |
| January 5 | 7.74° C | 45.93° F |
| January 4 | 7.73° C | 45.92° F |
| January 3 | 7.77° C | 45.99° F |
| January 2 | 7.71° C | 45.88° F |
| January 1 | 7.72° C | 45.89° F |
| December 31 | 7.78° C | 46° F |
| December 30 | 7.84° C | 46.11° F |
| December 29 | 7.8° C | 46.04° F |
| December 28 | 7.87° C | 46.16° F |
| December 27 | 7.87° C | 46.16° F |
| December 26 | 7.9° C | 46.23° F |
| December 25 | 7.83° C | 46.09° F |
| December 24 | 7.87° C | 46.16° F |
| December 23 | 7.95° C | 46.32° F |
| December 22 | 8.01° C | 46.43° F |
| December 21 | 8.1° C | 46.58° F |
| December 20 | 8.23° C | 46.82° F |
| December 19 | 8.29° C | 46.93° F |
| December 18 | 8.27° C | 46.88° F |
| December 17 | 8.26° C | 46.87° F |
| December 16 | 8.26° C | 46.87° F |
| December 15 | 8.27° C | 46.88° F |
| December 14 | 8.27° C | 46.88° F |
| December 13 | 8.25° C | 46.84° F |
| December 12 | 8.28° C | 46.9° F |
The actual nearshore temperatures may vary by several degrees and this can also be heavily affected by weather. Strong winds can cause cold, deep waters to replace the surface waters that had been warmed by the sun, and heavy rain can also reduce the temperature of the sea surface temperature as well.
Water temperature in San Juan Islands by month
The chart below shows the monthly average water temperature in San Juan Islands.
For more detailed information on how the sea temperature in San Juan Islands changes for each month of the year, choose from the months below.
San Juan Islands map and nearby water temperatures
Locations near San Juan Islands
Why measure sea surface temperatures (SST) in San Juan Islands?
The ocean covers about 71% of the Earth's surface, and scientists record the sea surface temperature (SST) of locations such as San Juan Islands because they want to understand and learn how the ocean communicates with the atmosphere of Earth.
SST is one measure that provides information on the global climate, and it can be used to predict the weather in San Juan Islands as well as atmospheric model simulations and to study marine ecosystems in the area.
Data source and citation
Raw data for the calculations made to find the sea surface temperature in San Juan Islands comes from the National Oceanic and Atmospheric Administration (NOAA) and their 1/4° daily Optimum Interpolation Sea Surface Temperature.
The water temperature data is constructed by combining observations from different platforms (satellites, ships, buoys, and Argo floats) on a regular global grid. A spatially complete sea surface temperature map is then built by interpolating to fill in gaps in the data.
If you'd like to use any of the information above in the format it is presented, please use the citation tool below.