White Sands National Park is open daily year-round except Thanksgiving and Christmas, although hours change seasonally. Missile tests can also cause temporary closures of roughly three hours. Winter afternoons are often mild by mountain standards, with December averaging about 60°F during the day, but nights average near 23°F. January averages 57°F/22°F and February 63°F/27°F. The National Park Service says an occasional winter storm can bring rain and limited snow, so the white landscape should not be mistaken for a warm one after sunset.
Sledding on the gypsum dunes is permitted year-round. The Park Service says waxed plastic snow saucers work best and notes that they can be rented or purchased at the park gift shop. Sledding is not allowed at the Interdune Boardwalk. Current hours and any missile-range closure should be checked before the drive.
Carlsbad Caverns offers the opposite kind of weather hedge: the Big Room averages 56°F, making the cave similar in January and July. Surface weather can still affect the trip, and entry procedures remain time-sensitive. The checked park page listed a final cavern entry at 2:30 p.m. and required natural-entrance hikers to be out by 3:30 p.m., but hours are volatile and should be verified. The park closes on Thanksgiving, Christmas, and New Year’s Day, and timed-entry reservations through Recreation.gov are strongly recommended.
Bandelier National Monument has a real mountain winter. It is generally open dawn to dusk except Christmas and days with heavy snow. December averages about 39°F/20°F, and the park reports around 11 inches of snow monthly from December through February. That is a different packing and driving problem from White Sands on the same trip.
Kasha-Katuwe Tent Rocks has the clearest calendar restriction: it closes annually from December 15 through January 31. Outside that closure, access is reservation-only Thursday through Monday from 8 a.m. to 1 p.m. and requires a Cochiti Pueblo Tribal Access Pass. Winter trails can be icy. A reservation should never be assumed to override the annual closure.