A friend of mine recently was forced to cancel a backpacking trip because Waterton Lakes National Park (Canada side of Glacier National Park in Montana) canceled his backcountry permit due to a forest fire flare up on the USA side of the border. I was in the park that day, the fire ignited and spread pretty quick, but was easily kept under control due to it's proximity to Upper Waterton Lake (and with the added help of a couple of Canadian helicopters).
What if you were already out in the backcountry when a fire started? Say you woke up one morning (or in the middle of the night) and you smelt smoke, then when you step out of your tent you can't see anything but a thick haze of ash all around you from a new fire which had very recently flared up near by and you're a day's hike from the trail head. What do you do?