How Crowded Is Fort Union Trading Post in September?
September is a busy month at Fort Union Trading Post National Historic Site, running about 1.4× the park's average month — roughly 11% of the year's visitors come in September. That puts it between the June peak and the January low. Overall our best-time score rates September as "Good" for a visit. Typical September weather averages a high near 75°F and a low around 46°F, with about 1.4" of precipitation. You'll get about 12.3 hours of daylight to explore.
Frequently Asked Questions
September is busy at Fort Union Trading Post National Historic Site (about 1.4× the average month). Our best-time score rates it "Good". The single best month overall is August.
The busiest month is June and the quietest is January. September sits at about 1.4× the park's average, or 11% of annual visitation.
Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-06-20.