I only traveled a few miles on the JMT this past weekend, but between Evolution Lake and Lake Helen it was beautiful. Snow is not an issue going over Muir Pass (just a couple easy snow covered sections of the trail on the east side and no snow patches to cross on the west side). The nights are getting colder and the days are getting shorter - it won't be long before we start getting snow again. The flowers were still beautiful even this late in the year. There were lots of swarming gnats at Wanda Lake and Evolution Lake, but the mosquitoes where not bad - just a bit annoying in the forested areas and when the breeze wasn't blowing. I did put some Deet on when I camped at Evolution Lake, but I didn't need it for most of the trip. Some pictures of my short trip this past weekend if you want to see what that short section of the JMT was like:
http://kathywing.smugmug.com/California-...5762609_fsSNpH5