How Crowded Is Whitman Mission in September?
September is a busy month at Whitman Mission National Historic Site, running about 1.2× the park's average month — roughly 10% of the year's visitors come in September. That puts it between the May peak and the December low. Overall our best-time score rates September as "Good" for a visit. Typical September weather averages a high near 80°F and a low around 44°F, with about 0.7" of precipitation. You'll get about 12.3 hours of daylight to explore.
Frequently Asked Questions
September is busy at Whitman Mission National Historic Site (about 1.2× the average month). Our best-time score rates it "Good". The single best month overall is August.
The busiest month is May and the quietest is December. September sits at about 1.2× 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.