Skip to main content

 Climates to travel
 World climate guide
 

Home Africa N.America S.America Antarctica Asia Caribbean Europe M.East Oceania

Home
Africa
N.America
S.America
Antarctica
Asia
Caribbean
Europe
M.East
Oceania

Climate - San Juan Islands (Washington)


Average weather, temperature, rainfall, sunshine hours

Flag - United States

San Juan Islands, map




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.
On Lopez island, the average temperature of the coldest month (January) is of 5.1 °C (41 °F), that of the warmest month (July) is of 15 °C (59 °F). Here are the average temperatures.
Lopez Island - Average temperatures
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Min (°C)233579101010754
Max (°C)891013171820201915119
Min (°F)363737414548505050454139
Max (°F)464850556364686866595248

In the southern part of Lopez island, Precipitation amounts to 490 millimeters (19.3 inches) per year: it is therefore quite scarce. It ranges from 20 mm (0.8 in) in the driest months (May, July, August) to 85 mm (3.3 in) in the wettest (December). Here is the average precipitation.
Lopez Island - Average precipitation
MonthJanFebMarAprMayJunJulAugSepOctNovDecYear
Prec.(mm)654540302030202025556085490
Prec.(in)2.61.81.61.20.81.20.80.812.22.43.319.3
Days141111867546111316112

The sea temperature ranges between 8 °C (46 °F) and 14 °C (57 °F). So, it is cold all year round. Here are the average sea temperatures.
Lopez Island - Sea temperature
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Temp (°C)888911131414131198
Temp (°F)464646485255575755524846

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




Search in the website:

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