You may hike on the dunes 24 hours a day. A free permit from the Visitor Center is needed if you plan to camp on the dunes at night. NPS/Scott Hansen Great Sand Dunes National Park and Preserve is open 24 hours a day, every day of the year. In winter, the Visitor Center hours are 9:00 a.m. to 4:30 p.m. daily, except for federal holidays, when the building is closed. The Visitor Center has longer hours in spring, summer and fall; call ahead at 719-378-6395 for specific Visitor Center information and hours for the time of your visit. In 2013, summer hours for the Visitor Center begin May 26; hours are 8:30-6 daily.