How Crowded Is Gateway Arch in September?
September is an average month at Gateway Arch National Park, running about 0.9× the park's average month — roughly 7% of the year's visitors come in September. That puts it between the July peak and the January low. Overall our best-time score rates September as "Excellent" for a visit. Typical September weather averages a high near 80°F and a low around 59°F, with about 3.4" of precipitation. You'll get about 12.2 hours of daylight to explore.
Frequently Asked Questions
September is average at Gateway Arch National Park (about 0.9× the average month). Our best-time score rates it "Excellent". The single best month overall is October.
The busiest month is July and the quietest is January. September sits at about 0.9× the park's average, or 7% of annual visitation.
Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-06-20.