Acadia National Park

Maine · Established February 26, 1919

Pink granite, spruce and sea fog where the mountains meet the North Atlantic

Area: 49,071 acres
Established: February 26, 1919
Recreation visits: 4,079,318 / yr
State: Maine
Highest point: Cadillac Mountain, about 1,530 ft (466 m)
Lowest point: Sea level, Atlantic Ocean

Acadia Weather Forecast

Loading the National Weather Service forecast for Acadia…

Seven-day outlook at the park's reference point (44.409, -68.248). Elevation changes everything in the mountains — expect colder, windier and wetter conditions on high ground.

Map of Acadia National Park

The Park

Acadia is a small park with an outsized coastline. Most of it spreads across Mount Desert Island, where a ridge of rounded granite mountains rises straight out of the Gulf of Maine, with outlying parcels on the Schoodic Peninsula and the island of Isle au Haut. Within a few miles you can climb from barnacle-crusted ledges through dark spruce woods to open summits scraped bare by ice.

Created by Congress as Lafayette National Park on February 26, 1919, it was the first national park east of the Mississippi River. Today it covers about 49,071 acres (198.6 sq km) and draws roughly four million visits a year, most of them in the short, bright Maine summer. The rest of the year belongs to fog, nor'easters, blazing October maples and long, quiet winters.

Geography

Mount Desert Island is the heart of the park, a lumpy granite island split nearly in two by Somes Sound, a long, steep-sided inlet that glaciers deepened. East and west of the sound, a chain of north-south ridges alternates with narrow lakes such as Jordan Pond and Eagle Lake, each lying in a valley the ice sheet gouged out.

Cadillac Mountain, at about 1,530 feet, is the highest summit in the park and the tallest point this close to the Atlantic shoreline along the eastern seaboard of North America south of Nova Scotia. From its bald crown the land falls away to a shore of pink cliffs, cobble beaches, sea caves and the rare sand pocket of Sand Beach.

Across Frenchman Bay, the Schoodic Peninsula offers a wilder, windier version of the same granite coast, while Isle au Haut lies well offshore to the southwest and is reached only by boat.

Landmarks

Cadillac MountainPeak · 1,530 ftThe park's highest summit, a broad dome of pink granite with views across Frenchman Bay.
Jordan PondLakeA clear glacial lake held in place by a ridge of glacial debris, framed by the Bubbles.
The BubblesPeakTwin rounded summits at the head of Jordan Pond, shaped by the passing ice sheet.
Bubble RockAreaA glacial erratic perched on the edge of South Bubble, carried here by ice from farther inland.
Sargent MountainPeakThe second great summit of the island, reached only on foot across open granite.
Champlain MountainPeakThe steep eastern ridge whose cliffs host the Precipice Trail and nesting peregrine falcons.
The BeehivePeakA small, sheer knob of granite above Sand Beach, climbed by an iron-rung trail.
Sand BeachCoastA rare sandy cove on a rocky coast, built largely from crushed shell fragments.
Thunder HoleCoastA narrow slot in the granite where incoming swells compress air and boom.
Otter CliffCoastPink granite cliffs dropping straight into the surf along the Park Loop Road.
Great HeadCoastA rocky headland east of Sand Beach where the shatter zone of the Cadillac granite is exposed.
Eagle LakeLakeOne of the largest lakes on Mount Desert Island, filling a glacier-cut valley.
Somes SoundCoastA long, deep inlet often called a fjord, nearly dividing Mount Desert Island in two.
Schoodic PointCoastWave-washed granite ledges cut by black diabase dikes on the park's mainland peninsula.
Isle au HautIslandA remote, boat-access island where much of the land is protected parkland.
Bass Harbor Head LightCoastA lighthouse on the rocky southwestern tip of Mount Desert Island, at the park's edge.

Geology

Acadia's story begins more than half a billion years ago on an ancient sea floor, where mud, sand and volcanic ash settled into layers. Heat and pressure later cooked those sediments into the Ellsworth Schist, a crumpled, banded rock that is the oldest in the Mount Desert region.

Around 450 million years ago, as a small drifting landmass called Avalonia pushed against North America, sand and silt piled onto that schist to become the Bar Harbor Formation, while nearby volcanoes spread the lavas and ash now known as the Cranberry Island Volcanics. Roughly 420 million years ago, great bodies of magma rose into these rocks and cooled slowly underground. The largest became the Cadillac Mountain Granite, whose pink color comes from its feldspar. Where the magma pried apart the rock above it, broken blocks were frozen in place, creating the shatter zone still visible on the east side of the island. Later, thin sheets of black diabase squeezed into cracks in the granite.

For hundreds of millions of years erosion stripped away the softer cover, leaving the tough granite standing as mountains. Then, over the last two to three million years, continental ice sheets repeatedly ground across the region. The last of them peaked about 18,000 years ago, polishing summits, carving U-shaped valleys and dropping boulders such as Bubble Rock far from their source.

The weight of the ice pressed the land down, so as the glaciers melted the sea flooded inland, lapping at beaches that now sit hundreds of feet above the waterline and laying down marine clays. As the crust slowly rebounded, lakes like Jordan Pond settled into their dammed valleys, and waves began the work they continue today: prying joints open, carving sea caves and sculpting the headlands.

Deep time

More than 500 million years agoMud, sand and volcanic ash accumulate in an ancient ocean and are later metamorphosed into the Ellsworth Schist.
About 450 million years agoAs Avalonia collides with North America, the Bar Harbor Formation and Cranberry Island Volcanics are deposited.
About 420 million years agoMagma intrudes and cools into the Cadillac Mountain Granite and neighboring granites, creating a shatter zone of broken rock.
After the granites formedDark diabase dikes are injected into cracks in the granite and surrounding rock.
Hundreds of millions of yearsLong erosion removes the overlying rock and leaves resistant granite ridges surrounded by lowlands.
About 18,000 years agoThe last ice sheet reaches its maximum, scouring the mountains and carving U-shaped valleys.
Following deglaciationThe depressed land is flooded by the sea, marine clays settle in lowlands, and ridges of glacial debris dam lakes like Jordan Pond.
By about 9,000 years agoThe land has rebounded and stabilized, and people are living in the region.

The rocks

Ellsworth SchistEarly Paleozoic or older
Thinly banded metamorphic rock of quartz, feldspar and green chlorite, the oldest in the area.
Bar Harbor FormationPaleozoic, about 450 million years
Layered brown to gray sandstones and siltstones laid down on top of the schist.
Cranberry Island VolcanicsPaleozoic
Light-colored lava flows and ash deposits exposed in the Cranberry Isles area.
Cadillac Mountain GraniteSilurian, about 420 million years
The largest granite body on Mount Desert Island, pinkish and coarse, forming the highest summits.
Shatter zoneSilurian
A jumble of older rock blocks trapped in granite along the eastern side of the Cadillac body.
Diabase dikesYounger than the granites
Black, fine-grained igneous rock filling fractures, well displayed at Schoodic Point.
Presumpscot FormationLate Pleistocene
Silt and clay laid down by the sea that flooded the land after the ice retreated, with marine fossils.

Trees, Plants & Ecosystems

867vascular plant species recorded

Granite summitsUpper ridges to 1,530 ft
Wind-scoured bedrock with tiny subalpine plants, blueberry and pitch pine tucked into joints and hollows.
Spruce-fir forestSea level to upper slopes
Dark boreal woods of red spruce and balsam fir, especially along the foggy coast and on the western side of the island.
Mixed hardwood forestLower and middle slopes
Birch, aspen, red maple and oak, much of it regrown after the great fire of 1947, turning the east side scarlet and gold in autumn.
Lakes, bogs and marshesValley floors
Glacial lakes, peat bogs and wetlands support pitcher plants, sundews, beaver, loons and frogs.
Rocky intertidal and shoreSea level
Barnacle and rockweed zones, tide pools and cobble beaches shaped by one of the coldest, most fertile coastal seas in the country.

Trees

Red sprucePicea rubensThe signature conifer of Acadia's coastal forest, thriving in cool fog and thin soils.
White sprucePicea glaucaA salt-tolerant spruce often found right at the edge of the sea.
Balsam firAbies balsameaA fragrant, spire-shaped fir that mingles with spruce in the dark coastal woods.
Eastern white pinePinus strobusThe tallest native pine of the Northeast, with soft needles in bundles of five.
Pitch pinePinus rigidaA tough, gnarled pine that clings to exposed granite ledges and ridgelines.
Jack pinePinus banksianaA northern pine that reaches a scattered outpost on the rocky ground of Schoodic Peninsula.
Eastern hemlockTsuga canadensisA shade-loving conifer of cool ravines and stream banks.
Northern white cedarThuja occidentalisA scaly-leaved conifer of swamps and wet shores.
Paper birchBetula papyriferaWhite-barked pioneer tree that surged back across the burned east side after 1947.
Quaking aspenPopulus tremuloidesAnother fire-follower whose leaves tremble in the lightest breeze and turn gold in fall.
Red mapleAcer rubrumThe source of much of Acadia's crimson autumn color.
Northern red oakQuercus rubraA hardwood of warmer, better-drained slopes on the island.

Wildflowers, shrubs & other plants

Lowbush blueberryVaccinium angustifoliumCarpets open summits and burns, ripening in late summer and turning red in fall.
Black huckleberryGaylussacia baccataA heath shrub of dry ledges that shares the mountaintops with blueberry.
RhodoraRhododendron canadenseA small native azalea that lights up bogs and wet ledges with magenta blooms in spring.
Sheep laurelKalmia angustifoliaA low evergreen shrub with pink flowers, also called lambkill for its toxic leaves.
Pitcher plantSarracenia purpureaA carnivorous bog plant that drowns insects in rain-filled leaves.
Round-leaved sundewDrosera rotundifoliaA tiny carnivore of peat bogs, its leaves beaded with sticky droplets.
BunchberryCornus canadensisA knee-high dogwood that blankets the forest floor with white bracts and later red berries.
TwinflowerLinnaea borealisA creeping boreal plant with paired, nodding pink bells.
Beach-head irisIris setosaA northern iris of wet coastal meadows and shorelines.
Black crowberryEmpetrum nigrumA mat-forming subarctic shrub hanging on at exposed, cold coastal sites.
Common juniperJuniperus communisA sprawling evergreen shrub of open granite and headlands.
Seaside goldenrodSolidago sempervirensA salt-tolerant goldenrod that blooms along the rocky shore in late summer.
OysterleafMertensia maritimaA blue-green, sprawling plant of cobble beaches whose leaves are said to taste of oysters.
Rugosa roseRosa rugosaA non-native Asian rose that has naturalized along beaches and roadsides.

Wildlife

38mammals
214birds
7reptiles
11amphibians
33fish

Mammals

White-tailed deerOdocoileus virginianusThe most commonly seen large mammal, grazing roadsides and forest edges.
Red foxVulpes vulpesA frequent sight along the Park Loop Road and carriage roads.
CoyoteCanis latransA wide-ranging predator of forest edges and fields, more often heard at night than seen.
American beaverCastor canadensisBuilds lodges and dams in ponds and streams, reshaping the island's wetlands.
River otterLutra canadensisA playful swimmer of lakes, streams and sheltered coves.
American minkMustela visonA sleek hunter of shorelines and marsh edges.
BobcatLynx rufusA secretive cat of dense woods, rarely seen.
North American porcupineErethizon dorsatumA slow, quill-covered browser often found up in conifers.
Snowshoe hareLepus americanusTurns white in winter to match the snow of the spruce woods.
Red squirrelTamiasciurus hudsonicusA noisy resident of conifer stands that caches spruce cones.
Eastern chipmunkTamias striatusA striped ground squirrel common around stone walls and trails.
Little brown batMyotis lucifugusOnce widespread, now much reduced across the Northeast by white-nose syndrome.
Northern long-eared batMyotis keeniiA small forest bat listed in the park checklist under an older scientific name.

Birds

Peregrine falconFalco peregrinusNests on cliffs such as Champlain Mountain, where trails close seasonally to protect them.
Bald eagleHaliaeetus leucocephalusPatrols the bays and islands year-round.
OspreyPandion haliaetusDives for fish in the sound and harbors from spring through summer.
Common loonGavia immerIts wavering call carries across the park's lakes in summer; many winter offshore.
Common eiderSomateria mollissimaA heavy sea duck that rafts in large flocks along the rocky shore.
Black guillemotCepphus grylleA black-and-white seabird with bright red feet, seen near ledges and islands.
Great black-backed gullLarus marinusThe largest gull in the world, a common presence on the coast.
Pileated woodpeckerDryocopus pileatusA crow-sized woodpecker that chisels rectangular holes in old trees.
Black-capped chickadeePoecile atricapillusMaine's state bird, a cheerful year-round flocker.
Hermit thrushCatharus guttatusFills summer evenings in the spruce woods with a flute-like song.
Black-throated green warblerDendroica virensOne of many warblers that nest in the park's mixed and conifer forests.
Northern parulaParula americanaA tiny warbler that nests in hanging lichens of foggy coastal forest.
Spruce grouseFalcipennis canadensisA tame, rarely seen grouse of dense conifer stands and bog edges.

Reptiles & amphibians

Common garter snakeThamnophis sirtalisThe snake most often seen basking on warm trails and ledges.
Smooth green snakeLiochlorophis vernalisA slender, bright green snake of grassy clearings.
Ring-necked snakeDiadophis punctatusA small, secretive snake with a golden collar, found under logs and stones.
Painted turtleChrysemys pictaSuns itself on logs in ponds and slow streams.
Common snapping turtleChelydra serpentinaA large, prehistoric-looking turtle of muddy ponds.
Spring peeperPseudacris cruciferIts high peeping chorus is one of the first signs of spring.
Wood frogRana sylvaticaA masked frog that freezes solid in winter and thaws to breed in early spring pools.
Eastern newtNotophthalmus viridescensIts bright orange land stage, the red eft, wanders damp forest floors after rain.

Fish

Brook troutSalvelinus fontinalisA native char of cold streams and lakes.
Lake troutSalvelinus namaycushA deep-water char of the island's larger, colder lakes.
Atlantic salmonSalmo salarPresent as landlocked salmon in some of the park's lakes.
AlewifeAlosa pseudoharengusA sea-run herring that migrates up coastal streams to spawn in fresh water.

Species totals are the park's certified NPSpecies checklist (occurrence: present).

Climate & When to Visit

Acadia has a cool, maritime version of a four-season New England climate. The Gulf of Maine keeps summers mild and delays both spring warmth and autumn chill, and it generates frequent fog, especially from late spring into summer when warm, moist air drifts over cold water.

Summer temperatures typically run from the mid-40s to around 90 F, with most days comfortably in the 60s and 70s near the shore. Frost usually arrives by mid-October, and snow can fall from November into April, adding up to about 73 inches in an average winter. Nor'easters bring heavy snow, rain and pounding surf, and late-summer tropical systems occasionally send large swells onto the coast. Summits are windier and cooler than the shoreline, and conditions can change quickly.

Spring
Slow to arrive. Days range from about 30 to 70 F, trails are often muddy or icy into May, and warblers pour in from mid-May.
Summer
The busy season, with temperatures roughly 45 to 90 F, frequent morning fog, and long daylight for hiking and paddling.
Autumn
Crisp days from about 30 to 70 F, first frost around mid-October, and peak foliage typically in early to mid-October.
Winter
Cold and quiet, with temperatures around 14 to 35 F, snow and ice on roads and trails, and most of the Park Loop Road closed to cars.

Weather hazards

Rogue waves and cold water: Stay well back from wet, dark rock at spots like Thunder Hole and Schoodic Point, especially when distant storms send large swells.
Fog: Dense fog can roll in within minutes, cutting visibility on the water, on roads and on open summits where cairns mark the route.
Nor'easters: Strong coastal storms bring heavy snow or rain, high winds and dangerous surf; check forecasts before winter visits.
Ice and exposure on rung trails: Iron-rung routes like the Precipice and Beehive are hazardous when wet or icy and are not suitable for descending.
Summit weather: Open granite ridges are exposed to wind, lightning and sudden cooling; carry layers even on warm days.

Acadia Questions

When is the best time to visit Acadia National Park?

Late June through mid-October offers the most reliable weather and full access to roads and trails. Early to mid-October brings brilliant fall color with cooler days and fewer crowds than midsummer, while September is often the sweet spot for clear skies and mild temperatures.

What is the weather like in Acadia?

Summers are mild and often foggy near the ocean, with highs mostly in the 60s and 70s F. Winters are cold and snowy, averaging about 73 inches of snow, and spring and fall swing between about 30 and 70 F. Weather can change quickly on the coast and on exposed summits.

How did Acadia's mountains form?

The peaks are made of granite that cooled from magma roughly 420 million years ago. After long erosion exposed the granite, ice sheets during the last few million years polished the summits, carved U-shaped valleys and left erratic boulders such as Bubble Rock.

Where can I see wildlife in Acadia?

Watch cliffs on Champlain Mountain for peregrine falcons in spring and summer, scan the shore for eiders, guillemots and bald eagles, and look for beaver activity in ponds at dawn or dusk. White-tailed deer and red foxes are common along roads and carriage roads.

Is Cadillac Mountain the first place in the U.S. to see sunrise?

Cadillac Mountain is one of the first places in the country to catch the sunrise for part of the year, which makes summit dawns hugely popular. A vehicle reservation is required for the summit road during the main season, so plan ahead.

Can you visit Acadia in winter?

Yes. Much of the Park Loop Road closes to cars, but snowshoers, cross-country skiers and hikers use the carriage roads and trails. Expect ice, short days and temperatures often in the teens and 20s F.

More parks in the East

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Sources: www.nps.gov · www.nps.gov · www.nps.gov · www.nps.gov · irmaservices.nps.gov · en.wikipedia.org · en.wikipedia.org · Official NPS site