How Crowded Is Gateway Arch National Park in September?

September runs about 0.9× Gateway Arch National Park's average month, which makes it an average month here — roughly 7% of the park's yearly visitors come in September.

In a typical September the park sees about 126,000 recreation visits, based on National Park Service monthly counts from 1979 to 2025.

That makes September the 6th-busiest of the park's twelve months, sitting between the July peak (2.9×) and the January low (0.3×).

On our Best Time to Visit score September rates 77/100 ("Excellent"), versus the top-rated October at 67/100 — pleasant weather with noticeably thinner crowds (shoulder season).

Typical September weather, from 1991–2020 NOAA climate normals at the nearest station, averages a daytime high near 80°F and an overnight low around 59°F, with about 3.4" of precipitation.

That average of about 70°F is a comfortable range for hiking and being outdoors all day.

Because June, July and August together draw about 48% of annual visitors, choosing September instead steps outside that summer crush — the single biggest lever on how crowded the park feels.

You'll have about 12.2 hours of daylight in September to explore — between the 9.3-hour midwinter low and the 14.7-hour summer high.

Park-wide, 2025 drew 2,209,028 recreation visits, down 13.8% from 2,563,052 in 2024.

Across the past decade overall visitation has risen about 37.8%, so a September visit is likely to feel busier than it did a few years ago.