June is baby-animal season in the Rockies, the height of the Pacific Northwest's rhododendron bloom and the opening month of Alaska's summer.
Bison calves ('red dogs') and elk calves are everywhere, grizzlies are active in the valleys, and the geysers steam under long early-summer days. Crowds are lighter than in July and August.
Hikes to do: Grand Prismatic Overlook, Fairy Falls, Storm Point Loop, Mount Washburn
Don't miss: Hayden and Lamar Valleys for wildlife, Grand Prismatic Spring, Grand Canyon of the Yellowstone
Tip: Snow can linger on high trails into late June. Mount Washburn may still have drifts.
Wildflowers bloom in the valley, moose feed in the willows, and snow still frosts the Tetons, the classic postcard look.
Hikes to do: Hidden Falls, Taggart Lake, String Lake Loop, Cascade Canyon
Don't miss: Schwabacher Landing at sunrise, Jenny Lake and Hidden Falls, Oxbow Bend for moose and reflections
Tip: High passes (Paintbrush, Static Peak) usually hold snow into July. Stick to the canyons.
Pacific rhododendrons bloom pink beneath the redwoods from late May through June, and the coast stays cool while inland California bakes.
Hikes to do: Lady Bird Johnson Grove, Fern Canyon, Tall Trees Grove, Stout Grove Loop
Don't miss: Lady Bird Johnson Grove in bloom, Fern Canyon's 50-ft fern walls, Elk herds at Prairie Creek
Tip: Tall Trees Grove and Fern Canyon (Gold Bluffs Beach) need free permits. See Permits & reservations.
The Alaska season is in full swing: boat tours run into the fjords, humpbacks and orcas feed, puffins nest on the cliffs, and there's nearly 19 hours of daylight.
Hikes to do: Exit Glacier Overlook, Glacier View Loop, Harding Icefield
Don't miss: Tidewater glaciers by boat, Exit Glacier, Harding Icefield overlook (later in the month)
Tip: The upper Harding Icefield Trail often holds snow until July. Check conditions before committing.
The ferries are running, moose calves are out, and the island's wild north woods are at their greenest. It's one of the least-visited parks in the system.
Hikes to do: Scoville Point, Stoll Trail, Mount Franklin, Lookout Louise
Don't miss: Rock Harbor, Scoville Point, Greenstone Ridge
Tip: June is black fly season. Bring a head net. Ferries and seaplanes book up; reserve early.
Early June is Acadia before the July rush: fresh green, cool ocean air, and lupine blooming across Mount Desert Island. Cadillac sunrise still needs a vehicle reservation.
Hikes to do: Ocean Path, Jordan Pond Path, South Bubble & Bubble Rock, Beehive Loop
Don't miss: Cadillac Mountain sunrise (reservation required), Jordan Pond and the Bubbles, Ocean Path from Sand Beach to Otter Cliff
Tip: Peregrine falcon nesting often closes the Precipice Trail into summer. Check the live alerts.
Early June is peak season for the synchronous fireflies, and rhododendrons and flame azaleas bloom at the high balds.
Hikes to do: Andrews Bald, Alum Cave to LeConte, Chimney Tops, Ramsey Cascades
Don't miss: Andrews Bald's azaleas, Clingmans Dome/Kuwohi, Cataloochee Valley elk
Tip: Viewing the Elkmont synchronous fireflies requires a lottery-issued pass. Watch the park's alerts in spring.