Gateway Arch in September: Crowds, Weather & What to Pack

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September is one of the best months of the year to visit Gateway Arch National Park: crowds run 29% of the July peak (139,931 average visits), days average 81°F with 12.5 hours of daylight. Computed from NPS and NOAA data.

Crowds in September

Gateway Arch averages 139,931 recreation visits in September — 29% of what July, the peak month, draws. Plan lodging and entries with that in mind.

Average visits (September)

139,931 (mean 2021–2025, NPS)

Share of the year

7% of annual visitation

vs. peak (July)

29%

Weather & daylight

Expect warm days (highs average 81°F), and nights stay mild (lows average 57°F). Average precipitation is 3.4″ for the month. Mid-month daylight runs 12.5 hours.

NOAA 1991–2020 monthly normals, station CAHOKIA ST LOUIS AP, IL US (4 mi from park coordinates, 413 ft elevation) — conditions vary inside the park, especially with elevation. Daylight computed for the 15th of September.

What to pack for Gateway Arch in September

Computed from the month's weather normals above — not a generic list.

Packable rain jacket — 3.4″ of precipitation is normal this month
Sturdy broken-in footwear, navigation and a basic first-aid kit — every park, every month

Common questions

Is Gateway Arch crowded in September?

No — September is one of the quieter months: 29% of the July peak, averaging 139,931 visits (NPS, 2021–2025).

What is the weather like in Gateway Arch in September?

Average highs of 81°F, lows of 57°F, 3.4″ of precipitation (NOAA 1991–2020 normals, CAHOKIA ST LOUIS AP, IL US station).

What should I pack for Gateway Arch in September?

Packable rain jacket; Sturdy broken-in footwear, navigation and a basic first-aid kit — the full weather-computed list is on this page.

See also: the best national parks to visit in September · Last verified 2026-07-16