The problem with Oregon is snow and skeeters anywhere from Sky Lakes north. Most of my experience has been in the Three Sisters Wilderness. I have hiked on bare ground there up to 6000 feet on the 1st of July, but this year I encountered considerable snow at 5000 feet at the same time. If the snow has receded far enough for easy hiking and navigation in July (and it is not raining), there will be loads of skeeters. I have friends who still talk about the clouds of skeeters I lead them into in July, 1981. They were much, much worse in early July, 2004. If you don’t want to deal with these annoyances, hike this area in August, the later the better. Hiking usually remains easy in these areas through September. The main nobo thru-hiker crowd comes through Oregon in August and they all contend with mosquitoes. I think they probably jog through most of Oregon and, consequently their journals seldom do Oregon justice.
Wayne Kraft