Of course, you're also going to be there when it's very warm, although I gather you already know that. So I would certainly take some sandals for casual use or around camp. But I'd arm myself with a bit more rugged footwear for the hike. Merrell's Chameleon Ventilator boots ($110; www.merrell.com), for example, have breathable mesh panels to offer good support without a big penalty in hot feet. The Reactor Ventilator Mid ($90), also from Merrell, is a mid-high boot that's even a little cooler.
For something even lighter, take a look at Nike's Air Zoom Orizaba ($90; www.nike.com), a very breathable, lightweight trail runner that might work just fine given the fact you plan to stick to trails and light loads. The Orizaba's have a lot of mesh to keep you cool, but still offer better foot protection than ordinary running shoes or walking shoes. And great traction. So I'd sign off on thosejust not sandals for any more than very short walks.
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