When the snow falls, Boulder's cross country community mobilizes! North Boulder Park, Flatirons Vista, and Doudy Draw all seem to have tracks magically appear when there's enough snow (actually, it’s the elves from the Boulder Nordic Club who do the hard work). Because snowfall is unreliable in town, there's also great networks of trails at Eldora Ski Area, Brainard Lake, and Moffat Tunnel that are about an hour from Boulder and are more consistently in. Eldora's groomed trails are part of the ski area's network while most other areas are free multi-use trails. Brainard Lake does have some ski-only trails. If you're the type to blaze your own path, try Moffat Road or Mammoth Gulch after a good snowfall -- you'll likely have the place to yourself.