Acadia in September: Crowds, Weather & What to Pack

Peak crowds · VisitWhen score 60/100 · #6 of 12 months

September is peak season — expect the year's biggest crowds at Acadia National Park: crowds run 83% of the August peak (662,737 average visits). Weather: highs average 71°F and lows 53°F, with 4.2″ of precipitation and 12.6 hours of daylight. Computed from NPS and NOAA data.

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Crowds in September

Acadia averages 662,737 recreation visits in September — 83% of what August, the peak month, draws. Plan lodging and entries with that in mind — book early and start days at dawn.

Weather & daylight

Daytime temperatures are comfortable (highs average 71°F), and nights stay mild (lows average 53°F). This is one of the wetter months (4.2″ of precipitation on average). Mid-month daylight runs 12.6 hours.

NOAA 1991–2020 monthly normals, station ACADIA NP, ME US (2 mi from park coordinates, 470 ft elevation) — conditions vary inside the park, especially with elevation. Daylight computed for the 15th of September.

What to pack for Acadia in September

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

• Rain shell + pack cover — 4.2″ of precipitation is normal this month
• Waterproof boots — plus navigation and a basic first-aid kit — 4.2″ of rain is normal this month

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Looking for a better window? The computed best months for Acadia are May and June.

Also at their best in September

Other parks whose computed September verdict is a best window — same NPS × NOAA formula:

• Wrangell–St. Elias in September — 25% of peak crowds, highs 56°F, score 84/100
• Guadalupe Mountains in September — 35% of peak crowds, highs 80°F, score 81/100
• Gateway Arch in September — 29% of peak crowds, highs 81°F, score 80/100
• Isle Royale in September — 39% of peak crowds, highs 65°F, score 79/100

Common questions

See also: the best national parks to visit in September · Last verified 2026-09-24