My son and I went up South Sister to the top on June 24th. At about a mile in on the trail the snow was skiable up to about 1/2 mile below the flats. The flats were 100% suncups for the two miles to the real slopes. The real slopes were good (but required a couple of dirty ridge walks) from about 7000 to 9000 feet. It was windy hail and poor visibility from there so we left our skis and walked to the top. Couldn't see well enough to tell you what the skiing might be like up there. However, on our day it was quite frozen above 8500 feet. Skiing was smooth from 9000 to the flats. It's getting late for skiing there, in my opinion, but if you must....we put the skis in the pack and climbed in sneakers all the way. It was 5 hours up and 2.5 hours down, to give you an indication of quality of the run.