When to go

Moab, Sedona, the Grand Canyon, and the red-rock country are built for jeep, ATV, canyoneering, and mountain-bike tours, but only when it is not dangerously hot. Spring and fall are the sweet spot; mild winters keep most tours running while summer midday heat shuts them down.

Colorado, Wyoming, and Montana pack a full adventure menu into a short high-country summer of rafting on snowmelt, zip lines, horseback, and alpine hiking, then flip to snowmobiling once the snow flies. June through September is the broad window; winter belongs to the snow tours.

Yosemite, Tahoe, and the Sierra Nevada deliver spring whitewater off the snowpack, then a long warm season for hiking, biking, and via ferrata. Big snow years stretch rafting deep into summer; the high country opens late after heavy winters.

Oregon and Washington save their dry, settled weather for summer, the window for rafting, zip lines, sea kayaking, and volcano hikes. Shoulder seasons are green and quiet but wet; the rivers run year-round but the comfortable season is short.

The Smokies and southern Appalachians have one of the longest adventure seasons in the country: dam-released whitewater, zip lines, ATV trails, and horseback all run for much of the year. Spring and fall are glorious; summer is humid but workable; foliage season is the headliner.

Alaska packs its glacier treks, rafting, wildlife, and flightseeing into an intense, light-filled summer from June to August. The shoulder weeks are unpredictable; winter is a different trip entirely: aurora viewing, dog sledding, and snowmachine tours.