I did this trek immediately following the Alaskan Kenai trek, so spent a week on the coast with that one and a week in the mountains on this one. By the end of August it was definitely chilly - don't expect nice weather - but wow, what an amazing part of the world. Coming from Australia I'd never seen a glacier before, let alone got to hike on one and try ice climbing. Denali National Park is truly awesome. It was heading into Fall on my trek - the oranges and yellows of the trees throughout the park were stunning. In Denali there are heaps of options for hiking or taking the wildlife bus, so it's fine for any fitness level, but of course there's no feeling like climbing a mountain, and there you get the best views. My friends though the photos I posted must be postcards - bring a good camera! Great trek.