San Juan Islands, Friday Harbor Weather & Seasons

San Juan Islands
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Summer is glorious in the San Juan Islands, with long hours of daylight and mild warm weather. Spring offers early blooms but also frequent rain. Fall and winter bring shorter days but little snow.

What is the weather like in the summer?

Summers in the San Juan Islands are quite mild, days hovering in the 70’s with cooler nights. The long hours of daylight help this warmth linger into the evening. Precipitation is very slight between June and September, but the occasional rainy day keeps the foliage lush into July.

What is the weather like in the fall?

Fall weather is similarly gentle, mostly shifting from 55 to 65 night and day. In September and October this mildness includes clear skies making it a great time to explore mostly deserted parks and beaches. Rain becomes more frequent going into November.

What is the weather like in the winter?

Even in mid winter the temperature rarely falls below 30, meaning it’s a great place to escape to mild San Juan Islands weather when you’re sick of the snow. The days, however, become very short this far north, with sunset around 4:00pm through December. The occasional Nor’easter coming down from the Yukon can bring incredibly stormy weather, with strong winds and brief freezes.

What is the weather like in the spring?

Spring temperatures are nearly identical to those in the fall, highs around 65/70, lows around 55. Rain should be expected, with the island receiving about 2 inches of rain each month between February and May. The fact that this is less rain than Seattle receives is a point of local pride. This is a great time for exploring the local communities while avoiding the summer crowds.

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