Although the park is officially open to travel all year, summer—June through September—is the “regular” season. From October until May, high-altitude roads are blocked by snow, as are most park trails in winter. All but one of the visitor centers are closed, and naturalist hikes and other activities are not scheduled after September 15. Camping is difficult from September to May because of adverse weather and limited facilities. However, the roads to both Estes Park and Grand Lake are usually open throughout winter, and accommodations are available in both gateway towns during the off-season.