Park Week’s default itineraries are warm-season. Each hub has a winter paragraph so you do not have to infer. This guide is the cross-cut: what generally stays open, what becomes the whole trip, and which paid activities simply stop selling.
Hubs that still resemble themselves
Grand Canyon South Rim
The village is open. The Rim Trail can be icy. Inner-canyon temperatures can be the best hiking weather of the year while the rim is frozen. The railway still runs. A geology walk still makes sense. Traction devices are not an aesthetic.
Zion
The canyon is quieter. The Narrows is a cold-water problem. Trails hold ice in shadow. Shuttle reductions can return private cars to the canyon — which helps until the lot is full. Angels Landing in ice is a different permit, not a flex.
Great Smoky Mountains
Valleys over ridges. Newfound Gap Road can close. Clingmans Dome Road is seasonally shut. Cades Cove can be the week. A Pigeon River trip may still exist; the five-day ridge stack does not.
Hubs that become a different trip
Olympic
Hurricane Ridge Road closes often. The coast is a storm show. The Hoh is a short, dark, wet day. Drop the whale-watch assumption. This can still be a good week if you wanted weather, not a ridge selfie.
Acadia
Services collapse. Park Loop segments close. Carriage roads can become ski tracks when snow holds. Boats largely stop. Bar Harbor in February is not Bar Harbor in July with cheaper parking.
Glacier
Going-to-the-Sun is closed as a through road. Boats and Jammers are off season. A winter visit can still be legitimate and limited. It is not this site’s five-day Logan Pass plan at a discount.
Paid activities in winter
Snowshoe tours on Hurricane Ridge (when the road is open), Zion photography walks, South Rim guided walks, and Smokies valley outings are the winter replacements. Whale-watches, most carriage bikes, Red Buses, and many Narrows products are not. Check Viator dates; empty calendars are information.
Insurance in winter
Still optional. The rational quote is more often weather plus prepaid mountain lodging than “I might not like the snow.” Flight schedules into small airports also get brittle. See the insurance guide.