In addition to the stated desireable climbing season of July-October, Dragontail is also one of the more reasonable large backcountry peaks to be climbed in the early season. Early season starts whenever the Mountaineer Creek Road opens to the Stuart Lake Trailhead, usually mid-April (call Leavanworth Ranger Station). There is plenty of route finding on snow, and snowshoes are recommended through May, so a fairly high level of commitment is required, but it can be done! as long as the avy danger is low and the snow is firm.
Excellent page - very helpful. However I believe that the dates where overnight permits are required are incorrect. The page states that permit season ends on October 15th. However the official USDA.gov page states that permit season ends in Oct 31. https://www.fs.usda.gov/wps/portal/fsinternet/cs/recarea?ss=110308&navtype=BROWSEBYSUBJECT&navid=110240000000000&pnavid=null&position=BROWSEBYSUBJECT&recid=58717&ttype=recarea&pname=Colchuck%20Lake%20Trail%20
Oh god...they extended it? That's a shame. Page edited to reflect that. Thanks