A-Basin  and or Keystone should be open by the end of the month

https://www.vaildaily.com/news/get-excited-more-colorado-ski-resorts-start-making-snow-as-storms-and-favorable-weather-loom/

Per usual, getting open by Thanksgiving weekend is the goal for destination resorts in Colorado.

Colorado ski resort opening days for the 2025-26 season - Summit Daily, posted early September 2025, recently updated