September is the insider's month: summer crowds thin, elk bugle, aspens turn gold in the Rockies and Great Basin, and Alaska's tundra turns red.
Elk rut season. Bull elk bugle in Moraine Park and Horseshoe Park at dawn and dusk, and aspen groves peak gold in the second half of the month. This is RMNP's most spectacular month.
Hikes to do: Bierstadt Lake, Bear Lake Loop, Alberta Falls, Cub Lake
Don't miss: Moraine Park and Horseshoe Park for the elk rut, Bear Lake Road aspens, Trail Ridge Road before it closes for winter
Tip: Timed entry still applies 9 a.m.–2 p.m. through mid-October.
Aspens and cottonwoods turn gold beneath the Tetons, elk gather and bugle, and summer's crowds are gone by mid-month. Moose rut too.
Hikes to do: Taggart Lake, Phelps Lake Loop, Two Ocean Lake, Signal Mountain
Don't miss: Oxbow Bend in fall color, Mormon Row, Signal Mountain
Tip: Nights drop below freezing and some facilities close after Labor Day.
Early September brings peak tundra color (red blueberry, gold willow), clearer skies and a good chance of an early aurora. Bus service winds down mid-month.
Hikes to do: Mount Healy Overlook, Savage River Loop, Triple Lakes, Rock Creek Trail
Don't miss: Fall colors along the park road, Savage River, Mount Healy Overlook
Tip: Services and buses end in mid-September. Check the dates before you book.
The second bear season. Bears gorge on spawned-out salmon along the Brooks River as they fatten up for winter, the lead-in to Fat Bear Week in early October.
Hikes to do: Brooks Falls Trail, Dumpling Mountain, Cultural Site Trail
Don't miss: Brooks River lower platform, Brooks Falls, Naknek Lake
Tip: Weather turns stormy. Floatplane delays are common, so build in buffer days.
Aspens turn gold along Wheeler Peak Scenic Drive, days stay mild, and the high trails remain open before the first snow.
Hikes to do: Alpine Lakes Loop, Bristlecone Pine Trail, Lehman Creek, Baker Lake
Don't miss: Wheeler Peak Scenic Drive aspens, Bristlecone grove, Lehman Caves
Tip: The scenic drive can close with early snow in late September or October.
September is one of the best months: summer crowds drop sharply after Labor Day, elk bugle at Mammoth, and bison and bears are active in cool weather.
Hikes to do: Upper Geyser Basin Loop, Mystic Falls, Bunsen Peak, Avalanche Peak
Don't miss: Mammoth Hot Springs elk rut, Lamar Valley, Upper Geyser Basin with fewer people
Tip: Early snowstorms can briefly close high passes. Check road status in the live alerts.
The rim is still open, the crowds are gone, and September's clear air shows the lake at its deepest blue.
Hikes to do: Watchman Peak, Garfield Peak, Mount Scott, Plaikni Falls
Don't miss: Rim Drive, Phantom Ship Overlook, Watchman Peak at sunset
Tip: Boat tours usually end in September. Check the schedule before you go.