Early season visits to Colorado ski resorts are down between 11 and 13 percent compared with last year because of low snow conditions, operators reported.

Colorado Ski Country USA, which represents 23 resorts, recorded 13 percent fewer visits at its member operations through Dec. 31, The Aspen Daily News reported.

Separately, Vail Resorts, which isn't part of Colorado Ski Country USA, reported visits were down 10.8 percent at its North American ski areas through Jan. 8. That includes four in Colorado, but state-only numbers weren't reported.

After a promising start in October, warm, dry weather reduced the amount of natural snowfall. So, many resorts relied on snowmaking, said Melanie Mills, president and CEO of Colorado Ski Country.

"Unfortunately, the weather stopped cooperating and the warm temperatures in November and December kept many skiers and riders from visiting the high-country," she said.

Rob Katz, CEO of Vail Resorts, said the company's Western U.S. sites had received "truly historic low snowfall."

"Fortunately, conditions have improved at our western U.S. resorts in the last week with expanded open terrain due to recent storms," he said.

"However, we still remain behind typical conditions for this time of year in terms of open terrain and base depth."

Aspen Skiing Co. said snowfall has improved recently, with up to 17 inches falling in the past week. Storms last week allowed Aspen to open more terrain.

Courtesy USDA

Colorado Ski Country USA noted the state's historically snowiest months are still ahead.

Snowpack in the Colorado mountains ranged from 34 percent to 84 percent of the long-term average on Sunday, with the southwestern corner of the state hardest hit.

Drought conditions have spread across virtually all of Colorado, according to the U.S. Drought Monitor, a federal agency that tracks conditions nationwide.