The best time of year along the Rim is that of early to mid October - weekday - when the horses are in their pastures and the people back in their towns. By October, however, it is also a question of how much time remains before the hiking season is ended by the onset of winter. Again, as is the case of dust, a shorter ground clearance means trouble and potentially early end to the season.
Weather in the mountains can be very fickle. The Little Girl and I arrived at Camp Lake at about 2 pm with cloudless skies. Two hours later, it is raining and lightning is coming down. Two more hours and there is a beautiful sunset. Be prepared for the mountains.
Thunderstorms can lead directly to forest fires. Be aware of forest conditions before going in. If conditions are dry, lightning strikes can quickly lead to bad case scenarios. In this case, a small fire had been started from the thunderstorm the day before. I watched a Forest Service smoke plane and another helicopter as they circled the small blaze. I was going out that day anyway, but still mentioned to the other people around the lake about the fire - you couldn't see it from Camp Lake - and as I was driving out, I saw a Forest Service fire crew driving into the trailhead. The Forest Service is usually right on top of things and most fires start slow. But not all. Be watchful.
Another thing forest fires can do is make you trip a lot more meaningless in regards to hazing up potential views. Jefferson Park is one of the prettiest places in Oregon, but a couple of years ago, forest fire smoke made it not the place to be.
In August and early September, the area is very dry and can be very hot. The dust on the trail can be inches thick - not good if you are not leading the way or have a ground clearance of four inches.