I answered my own question regarding the Holston with a brief trip to the river this morning. I do not have a thermometer but I could feel that the water was quite warm. Cherokee must be turning over or something. I fished a riffle for about an hour and, while there were some caddis of various sizes hatching, there was very little trout action. I got no bites.
However, it was a nice morning to be on the water and watching huge flocks of swallows crashing bugs up and down the river was worth the price of admission alone. That and I foul hooked a 24"+ buffalo that tore my drag like an Atlantic Salmon until it finally snapped my 5x tippet (at the surgeon's knot, not the Pitzen knot...).