San Juan Islands, WA
Today’s Forecast:
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Today’s Report:
Boating
Good for boating. High near 61°F. Light wind (8 mph).
- Temp: Marginal weather factor
- Rain: Favorable conditions
- Wind: Favorable conditions
- Thunderstorm: Favorable conditions
Paddling
Good for paddling. High near 61°F. Light wind (8 mph).
- Temp: Marginal weather factor
- Rain: Favorable conditions
- Wind: Favorable conditions
- Thunderstorm: Favorable conditions
Biking
Excellent for biking. High near 61°F. Light wind (8 mph).
- Temp: Favorable conditions
- Rain: Favorable conditions
- Wind: Favorable conditions
- Thunderstorm: Favorable conditions
About San Juan Islands
San Juan Islands is a Washington destination for archipelago-wide ferries, boating, kayaking, cycling, beaches, and island-to-island trips.
Make the Most of a San Juan Islands Day
Use marine forecasts and ferry notices together. Wind, current, fog, cold water, and limited sailings can change an island itinerary quickly.
Weather Tips for San Juan Islands
- Check marine wind, fog, tides, current, surf, or ferry conditions as appropriate; the inland temperature alone is not enough.
- Cold water, waves, current, wind, and lightning should guide water plans more than sunshine alone.
- After steady rain, favor paved or well-drained surfaces until natural trails recover.
- Summer smoke, winter access, shoulder-season closures, and shorter fall daylight can matter even during an otherwise mild forecast.
Nearby Towns and Areas
This page can also be useful when planning outdoor time near:
- Friday Harbor
- Orcas Island
- Lopez Island
- Shaw Island
- Roche Harbor
- Rosario Strait
- San Juan Channel
Plan Around the Conditions, WA
Use the forecast to choose the best version of a San Juan Islands day. Match wind, precipitation, smoke, water conditions, trail surfaces, road access, temperature, and daylight to the activity that gives your group the safest and most comfortable plan.
7-Day Forecast for San Juan Islands
San Juan Islands Weather by Season
Winter
Winter at San Juan Islands is cool and wet west of the Cascades, with occasional lowland snow or ice. Shaded roads, bridges, docks, and trails can remain slick after other surfaces clear.
Spring
Spring around San Juan Islands brings changing conditions, rising rivers, wet trails, and lingering mountain snow. Cold water from rain and snowmelt remains a major planning factor. Coastal wind and tides still control shoreline access.
Summer
Summer at San Juan Islands is usually the driest and most dependable season, but wildfire smoke, fire restrictions, heat, and afternoon thunderstorms can interrupt plans. Use calmer mornings for boating or paddling and keep a shore-based backup. Marine fog and cold water can persist even on warm inland days.
Fall
Fall at San Juan Islands brings cooler temperatures, shorter daylight, changing color, and the return of wetter weather west of the Cascades. Water cools faster than the air, increasing cold-water consequences. Check seasonal facility hours and allow extra time on busy event or salmon-viewing weekends.
Key Climate Data Points
- Annual average temperature: around 50–52°F, using the relevant local or regional elevation context.
- Annual snowfall: snow is usually limited at low island elevations, though occasional winter events occur, with substantial year-to-year and elevation variation.
- Warmest months: July and August are normally warmest.
- Coolest months: December and January are typically coolest.
- Wettest season: November through January.
- Driest season: July and August.
- Best outdoor window: May through September for boating, paddling, cycling, and camping.