How Crowded Is San Juan Island in May?
May is an average month at San Juan Island National Historical Park, running about 1.1× the park's average month — roughly 10% of the year's visitors come in May. That puts it between the July peak and the January low. Overall our best-time score rates May as "Good" for a visit. Typical May weather averages a high near 64°F and a low around 44°F, with about 1.1" of precipitation. You'll get about 15.0 hours of daylight to explore.
Frequently Asked Questions
May is average at San Juan Island National Historical Park (about 1.1× the average month). Our best-time score rates it "Good". The single best month overall is April.
The busiest month is July and the quietest is January. May sits at about 1.1× the park's average, or 10% of annual visitation.
Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-06-20.