Cadillac Mountain
The reservation season normally extends into October. Keep a windproof layer for the exposed summit and check the actual end date.
September · Cadillac Mountain
What to see and do in Acadia in September
Choose a September outing that fits the route, weather and effort involved.
Park Loop Road
Use the normally operating loop for coast and woodland stops; choose foliage dates flexibly rather than guaranteeing a peak week.
September · Park Loop Road
Acadia weather in September
September’s normal high is 71°F and low is 53°F, with 4.22 inches of precipitation. The Acadia NP NOAA station sits at ~470 ft near park headquarters, about 2.5 miles from the NPS API coordinate, so these numbers describe inland Mount Desert Island, not the summits or the open coast. NPS says weather on Cadillac Mountain (1,530 ft) and the other peaks can be very different from Bar Harbor.
Cooler Hotter
Jan
High33°F
Low15°F
Precip · in4.48
Feb
High35°F
Low18°F
Precip · in3.84
Mar
High42°F
Low25°F
Precip · in4.94
Apr
High53°F
Low35°F
Precip · in5.15
May
High65°F
Low45°F
Precip · in4.50
Jun
High74°F
Low54°F
Precip · in4.28
Jul
High79°F
Low60°F
Precip · in3.27
Aug
High78°F
Low60°F
Precip · in3.45
Sep
High71°F
Low53°F
Precip · in4.22
Oct
High59°F
Low43°F
Precip · in5.86
Nov
High48°F
Low33°F
Precip · in5.89
Dec
High38°F
Low22°F
Precip · in5.66
Acadia crowds in September
September averages 662,737 recreation visits, 83% of the peak monthly average in August.
LowestLowModerateHighPeakAverage month: 332,670September
Tips for your September visit
Check the approach before choosing the rest of the day.
APark Loop Road Entrance (Route 233)BSand Beach Entrance StationCyear-round access at Schooner Head RoadDBlackwoods Campground Entrance StationESeawall Campground Entrance StationFSchoodic Entrance (SERC)
- Park boundary
Park Loop Road Entrance (Route 233)
Normal road approach, subject to weather and individual site restrictions.
How we built this page.
An independent guide using official data. Not affiliated with or endorsed by the National Park Service.
- Crowds
- 2021–2025 monthly averages. NPS recreation visits, compared with the park’s own busiest month. Visits are not unique visitors or a count of people on a trail.
- Weather
- 1991-2020 climate normals. NOAA’s Acadia NP, ME station. These describe typical weather at the station, not every part of the park or a forecast.
- Roads & lodging
- Normal seasonal schedules. NPS guidance and official operator information. Confirm access, hours and availability before you travel.
Historical records and data-quality checks
- Visit history: 1979–2025 NPS monthly recreation visits.
- Weather history: 1982–2025 daily observations, separate from climate normals. We average daily highs and lows and total the rain for each month.
- Complete months only: every day must pass our quality checks for that metric. Missing or incomplete records stay blank; we never interpolate.
- Excluded measurements: flagged, presumed-zero and lagged values. Trace rain counts as zero measurable rainfall.