
I think some of these native deciduous trees shed some of their first Spring leaves (their oldest leaves) in August. Possibly by lightening their load, they reduce their water need by reducing the surface areas of leaves losing water through respiration. Conifers, like hemlock and cedar routinely loose their tops during extreme drought. Not much of stretch of imagination to guess that it is happening way early in this drought year.
The upside of dead trees is new undergrowth (deer chow) over the next few years, which of course, means more baby deer. The downside - more fuel for fires.