Skip to main content

 Climates to travel
 World climate guide
 
 
 Home
 Africa
 N.America
 S.America
 Antarctica
 Asia
 Caribbean
 Europe
 M.East
 Oceania
 All the countries
 Home
 Africa
 N.America
 S.America
 Antarctica
 Asia
 Caribbean
 Europe
 M.East
 Oceania
 All the countries

Climate - San Juan Islands (Washington_state)


Average weather, temperature, rainfall, sunshine hours

Flag - United States

San Juan Islands, map


You are here: Home --> North America --> United States --> San Juan Islands



The climate of the San Juan Islands is sub-oceanic, with quite mild, rainy winters and mild, fairly sunny summers.
The archipelago is located in the northwest of Washington state, east of the Canadian island of Vancouver, between the Strait of Georgia and the Strait of Juan de Fuca. The main islands are Orcas, San Juan, Lopez, Shaw (the first four, served by the Washington State Ferries), Decatur and Blakely.
Even though we are in a humid area, the islands are affected, especially in the southern part, by the rain shadow generated by the Olympic Mountains. For this reason, rainfall is lower than 1,000 millimeters (40 inches) per year, and it drops even below 500 mm (20 in) in the southernmost part of Lopez and San Juan islands. In Olga, on Orcas Island, it amounts to 735 mm (29 in).
Although the winter is mild enough, there can sometimes be cold waves, sometimes even in November, with lows going down to -7/-8 °C (18/19 °F) or even below. The cold wind blows from the north-east, from the Fraser Valley, and mainly affects Orcas Island and the small northern islands.
Snow is rare due to the prevalence of mild currents from the ocean. In a year, 17 cm (6.7 in) of snow fall on Lopez Island.
In summer, it rarely gets hot because of the influence of the ocean, and even when it does, the temperature drops a lot at night. Generally, the temperature does not go above 33/34 °C (91/93 °F) on the hottest days, but sometimes it does not even reach 30 °C (86 °F) for a whole month. During the exceptional heat wave of late June 2021, the temperature reached 38 °C (100 °F) in Friday Harbor.
In Friday Harbor, a town located on San Juan Island, the average temperature of the coldest month (December) is of 5.3 °C (41.6 °F), that of the warmest month (August) is of 16.4 °C (61.6 °F). Here are the average temperatures.
Friday Harbor - Average temperatures (1991-2020)
MonthMin (°C)Max (°C)Mean (°C)Min (°F)Max (°F)Mean (°F)
January385.6374742.1
February295.8364942.5
March4117.5385345.5
April5149.5415749
May71812.2446454
June92014.6486858.2
July102216.2507261.2
August102316.5507361.6
September92014.4486858
October71510.7445851.3
November4117.4405145.4
December385.3374641.5
Year61510.542.85951

Precipitation amounts to 470 millimeters (18.5 inches) per year: it is therefore quite scarce. It ranges from 10 mm (0.4 in) in the driest month (July) to 75 mm (3 in) in the wettest (November). Here is the average precipitation.
Friday Harbor - Average precipitation
MonthMillimetersInchesDays
January702.817
February401.614
March351.414
April25110
May301.210
June200.88
July100.45
August200.88
September25112
October602.415
November75316
December602.416
Year47018.5144

The sea temperature ranges between 7.5 °C (46 °F) and 13.5 °C (57 °F). So, it is cold all year round. Here are the average sea temperatures near Lopez Island.
Lopez Island - Sea temperature
MonthCelsius (°C)Fahrenheit (°F)
January7.546
February7.546
March847
April949
May1152
June12.555
July13.556
August13.557
September1355
October1151
November9.549
December8.547
Year10.450.7

San Juan Islands

Best Time


The best time to visit the San Juan Islands is summer, especially in July and August, since it is the mildest, driest and sunniest period of the year. June and September are also acceptable months.

Back to the climate of Washington state.


© Copyright Climatestotravel.com. 

Back to North America --> United States

All the countries


Share this page:
Facebook Twitter LinkedIn Whatsapp Email



 Continents:
 Africa
 North America
 South America
 Antarctica
 Asia
 Caribbean
 Europe
 Middle East
 Oceania

Search in the website:

Home About Contact Us Link Policy
Home
About
Contact Us
Link
Policy