well, my pin oaks have almost completely lost their leaf-set twice this year. Once from the flash frost and then again from this drought.

This images are rather huge, so they're not very dial-up friendly, but take a look at my backyard.

This really doesn't answer your question, but I've got a weird one.

NOT because of the drought (this tree gets watered twice a week if it doesn't rain), but perhaps because of the heat and/or the late freeze, my scarlet buckeye is right now flowering for the second time this year. It successfully flowered in the spring (didn't get frozen), and now it's flowering on NEXT year's buds. I'm sad, since it probably means it won't have any flowers in the spring. Sniff.

As you would suspect there is no lush grass, trees are losing leaves prematurely, especially dogwood trees and oaks. It is sad. Watering helps but not much, just enough to keep flowers and some veggies alive but not producing like they should. The ground is hard and baked. The worst I have ever saw in my lifetime. Now many places are restricting watering and if we don't get rain soon there will be mandatory restrictions of no outside watering. Hopefully the Fall and Winter will bring some much needed cooler temps. and rainfall.

Wow. Some of those pics are amazing. It looks like late fall/early winter in places! If the weather turns very wet this fall, with obviously cooler but still warmish spring-like temperatures, I would not be surprised if many of your large trees (like oaks) and shrubs leaf out or flower again. In other words, many trees may be interpreting this summer as "winter" and then these same trees may get confused by thinking fall is spring. I saw this happen in my area many years ago after a hurricane. Hurricane Bob (August 1991) gave us a direct hit. Towns on the ocean experienced hurricane force winds with little or no rain, near the end of the storm. This created incredible salt spray that dessicated all of the trees in August--with the leaves turning brown and falling off. But by the end of Septemember and October, pleasant temperature and rainfall caused many of these trees to leaf out and flower all over again. It does stress the trees but as long as conditions return to normal--for a while--most will recover.

Something similar to what you describe may occur. The plants aren't going to think it's spring; they know what season it is. Trees, shrubs, and perennials may drop their leaves to conserve moisture as a self-protective mechanism. If conditions change before it gets cold, the plants may try to put out another set of leaves. If the leaves don't develop long before it gets cold, the plant may expend more energy producing the leaves than it can make before winter. The current drought stress plus having to produce new leaves can deplete the plants energy reserve required to break dormancy and produce new leaves in the spring.

Another set of factors that may need to be considered is stress related disease and insect problems. The drought may predispose many plants to attack from pests that could normally be fought off. Trees and shrubs, especially, may experience many problems next year or even a few years down the line. Often the real cause of a tree or shrub's problem is long forgotten before the symptoms are evident. By then, it's often too late to take action.

FWIW central and northern Alabama have been drier longer and hotter longer than we have . We reached exceptional extreme drought in June; parts of AL have had it since early spring. Back in June some parts of TN were normal. Now we're all extreme drought or worse.
But we are still hurting. Tulip poplars were badly damaged by our very late Easter hard freeze; now they are dropping leaves almost everywhere. Box Elders may be leafless in several more days. Kudzu is wilted as are other common weeds.
We are out in the country and for the past three months, our forest trees have been dropping large limbs. Not limbs that show rot or insect damage after falling, but just limbs with leaves intact. We've got about 100 acres of woods and will probably take so much of the downed wood this fall as to heat our house for several years. And that's without getting into the deep part on the cliff.
We have rocks emerging from the hay fields where there were less than two square feet of rock showing, there's now about six square feet as the clays shrink.
South facing mountains sides look more damaged than north facing sides. On some mountains I watch I'd guess at least three percent of the trees are already dead (foliage and all). Every day I see more dead trees from my kitchen window, and these are trees that are massive and old. And sad.

Maples, dogwoods, white pines, and tulip poplars seem especially hit. One need only look out over a wooded area to see it speckled with dead trees. Can't tell if its the drought or the adelgid (sp?)(or both) thats hitting the hemlocks. Sadly, hemlocks may be nearly gone from the Knox area in a few years. Theoretically, what changes in tree species could one possibly expect if such summer conditions continued (off and on) into the future? My guess would be an increase in southern pine, cedar, and more xeric oaks (blackjack, southern red, post). Losers would be tulip poplar, American beech, maple (especially sugar), and white pine in higher elevations. Is my assumption correct? What new species might move in? Loblolly pine is already becoming naturalized.