Unfortunately, just as the fire really started cranking the sky began to darken. The rumbling of thunder was getting closer. It became obvious I was gonna get wet, and soon. It wasn't much but I did have one of those $.99 disposable ponchos with me. It was pretty thin but unlike a can liner it did have a hood.
I think it was in Hood's woods or some video I learned to cut the 55 gal bag along the bottom scene from the corner just a bit. That way, only your face is exposed to the elements. Don't bother cutting arm holes since you want to keep as waterproof as possible.
My contractor grade bags are less than .99 and I like their multitude of uses. I always have two.