Vail Mountain is now 100 percent open for 2018-19 season: VAIL, Colo. – Dec. 28, 2018 – Following 13 inches of snow in the past seven days and with more in the forecast as the New Year approaches, Vail Mountain is now 100 percent open. All lifts at Vail Mountain are operational for the season, providing access to 5,289 skiable acres of terrain, the most currently open in Colorado.