US travel guide September 2025: Where to go watching wildlife

September is one of the best months to explore America’s national parks. The weather is still warm, the snow has melted from many higher elevation trails, and after Labor Day the crowds start to thin as families return home for the school year.

In northern states, roads are still open and conditions are perfect for late-summer hikes. In the Southwest, the scorching heat eases, especially toward the end of the month. And if you’re lucky, a few parks even offer the first glimpse of fall colors.

From rugged mountains to remote islands, here are the parks that shine this September.

In Wyoming’s northwest corner, the jagged Teton Range rises dramatically above Jackson Hole Valley. Grand Teton National Park is a perfect for hikers, climbers, and anglers, with crisp mornings and golden light that makes the mountains glow. In September, highs hover in the 70s, but nights dip close to freezing, so it is recommended to pack layers. Wildlife is especially active this month—moose and elk move through the valleys, and bears forage before winter. With Yellowstone just up the road, this is a two-for-one adventure in the American West.

Just off Southern California’s coast, five wild islands make up Channel Islands National Park. September brings calm seas and perfect weather for snorkeling, kayaking, and spotting marine life. Santa Cruz Island’s sea caves beg to be explored, while San Miguel hosts thousands of seals at Point Bennett. The cliffs of Anacapa are dotted with seabirds, and Santa Rosa shelters rare Torrey pines. With highs in the 70s and long daylight hours, it’s the ideal time to enjoy the park’s rugged beauty and rich biodiversity.

On the Atlantic coast of Maine, Acadia is nicknamed the “Crown Jewel of the North Atlantic Coast.” Its granite headlands, pine forests, and sweeping ocean views are at their most comfortable in September, when the air is crisp but not yet cold. Visitors can drive the historic carriage roads, hike over 150 miles of trails, or simply watch the sunrise from Cadillac Mountain—the first place in the U.S. to see the sun. With fewer crowds and less rain than later months, Acadia feels both wild and welcoming this time of year.

Nevada’s Great Basin National Park is a study in contrasts—limestone caves below, towering peaks above. September brings a burst of fall color, as aspens turn gold and orange by the third week of the month. Hike up Wheeler Peak, Nevada’s second-highest summit, or explore the intricate Lehman Caves. The skies here are some of the darkest in the country, making stargazing an unforgettable part of the experience. Days are pleasantly warm, but nights carry a cool bite, perfect for cozy campfires.

In northern Colorado, Rocky Mountain National Park offers alpine lakes, waterfalls, and some of the most breathtaking drives in the country. Trail Ridge Road remains open in September, winding past aspen groves that start to glow with autumn colors. Elk are in rutting season, and their bugling calls echo through the valleys. Daytime highs are comfortable in the 70s, but mornings are brisk. Whether you’re hiking around Bear Lake or climbing Longs Peak, September gives you the Rockies at their best.

Straddling the border of Montana and Canada, Glacier is known as the “Crown of the Continent.” September offers warm days, cool nights, and far fewer visitors than summer’s peak. With more than 130 lakes and a million acres of wilderness, it’s a paradise for hikers and wildlife watchers. Mountain goats and bighorn sheep roam the cliffs, while grizzly bears prepare for hibernation. The Going-to-the-Sun Road remains open, offering one of the most scenic drives in the U.S. before snow returns.

For a tropical twist, head to the South Pacific. The National Park of American Samoa, spread across three islands, preserves coral reefs, lush rainforests, and vibrant Samoan culture. September is the driest month, making it the perfect time to hike Mount ‘Alava, snorkel in clear lagoons, or relax on the pristine Ofu Beach. With highs around 84°F and warm seas, this park feels worlds away from the mainland—a rare mix of wilderness and tradition.