How Crowded Is San Juan Island in August?
August is a very busy month at San Juan Island National Historical Park, running about 1.7× the park's average month — roughly 14% of the year's visitors come in August. That puts it between the July peak and the January low. Overall our best-time score rates August as "Fair" for a visit. Typical August weather averages a high near 73°F and a low around 50°F, with about 0.7" of precipitation. You'll get about 14.1 hours of daylight to explore.
Frequently Asked Questions
August is very busy at San Juan Island National Historical Park (about 1.7× the average month). Our best-time score rates it "Fair". The single best month overall is April.
The busiest month is July and the quietest is January. August sits at about 1.7× the park's average, or 14% of annual visitation.
Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-06-20.