Early winter · Weather & things to do
San Juan Island in December
This is the coldest month in San Juan Island: highs average 44°F (7°C) and lows 39°F (4°C), with about 5.4 in (137 mm) of rain.
With a comfort score of 37/100 (12th of 12), it's one of the toughest months, held back mainly by cloud cover.
- Avg high
- 44°F (7°C)
- Avg low
- 39°F (4°C)
- Rain
- 5.4 in (137 mm)
- Humidity
- 86%
- Cloud cover
- 83%
- Daylight
- ~8 h 06 min
- Comfort score
- 37/100 · Tough
What December feels like
Cool days top out near 44°F (7°C), better for brisk walks than lingering outside.
Lows average 39°F (4°C).
Rain is a real factor, with about 5.4 in (137 mm) across the month.
Skies are often grey, with average cloud cover around 83%.
Only about 8 h 06 min of daylight means early sunsets.
Plan around December
December is one of the lower-scoring months here; the best are June – September.
- Inside the wettest three-month stretch, November – January.
- Shortest days of the year, about 8 h 06 min of daylight.
- Comfort slips from 44/100 in November to 37/100.
- Our Puget Sound Islands route recommends May – Sep, so December falls outside its suggested window.
What to pack for December
- Insulated jackethighs only 44°F
- Rain jacket and waterproof shoes5.4 in of rain on average
- Comfortable walking shoesmost picks involve some walking
What to do in San Juan Island in December
Wet days call for a roof: these picks favor sit-down and indoor stops, plus a few for drier spells.
Roche Harbor
Historic marina village with a flag ceremony at sunset in summer.
Whale watching from Friday Harbor
Boat tours to find orcas, humpbacks and minke whales in Haro Strait.
English Camp
British garrison site with restored buildings and a Young Hill hike.
Duck Soup
Long-running island restaurant using local produce and seafood.
Why now A sit-down stop to wait out showers in a month with 5.4 in of rain.
American Camp
Open prairie and beaches from the 1859 Pig War, part of the national historical park.
Nearby in December
- Victoria in December~18 mi · highs 44°F, 5.4 in rain · similar daytime temperatures, about as wet
- Vancouver in December~52 mi · highs 40°F, 11.6 in rain · 2°C (4°F) cooler by day, wetter
- Olympic NP in December~57 mi · highs 31°F, 10.6 in rain or snow · 8°C (14°F) cooler by day, wetter
- Bainbridge Island in December~67 mi · highs 44°F, 6.9 in rain · similar daytime temperatures, wetter
NASA POWER 2001–2025 monthly averages on a ~50 km grid. Comfort scores weigh temperature, rain, humidity and cloud: see how we score each month. Check a forecast before you go.
San Juan Island in December: quick answers
Is December a good time to visit San Juan Island?
It's one of the tougher months here, scoring 37/100, held back mainly by cloud cover. The best months are June – September. Expect highs of 44°F (7°C) and 5.4 in (137 mm) of rain. Our Puget Sound Islands route recommends May – Sep, so December is outside its suggested window.
How cold is San Juan Island in December?
Average highs are 44°F (7°C) and average lows 39°F (4°C), making it the coldest month by daytime highs.
Does it rain a lot in San Juan Island in December?
Yes: about 5.4 in (137 mm) of rain falls across December on average, the 3rd-wettest month of the year. The annual total is about 39.0 in (991 mm).
What should I pack for San Juan Island in December?
Bring insulated jacket (highs only 44°F), rain jacket and waterproof shoes (5.4 in of rain on average) and comfortable walking shoes (most picks involve some walking).
More on San Juan Island
Planning San Juan Island in December?
Plan it together in TripsCircle: one itinerary, one shared packing list and costs split as you go.