Eventually, all things will attain an equillibrium, but it is the speed at which that equillibrium state occurs that usually chills us mammals to the bone or fries us like bacon. Color aside, your LGD's hair length and coat condition are crucial factors determining its ability to tolerate the daytime heat load. Ta is the Temperature at the tip of the hair. Ts is the Temperature at the surface of the skin.
L is the distance between the tip of the hair and the surface of the skin.
F is a number, determined through experiment, which estimates the ability of a hair to conduct heat. I'll ignore it here. Okay, now a few facts. The dog's skin will stay cool longer. If the dog has been clipped to 1-inch, then conductance, C , will remain at 65 and the dog's skin will heat quickly.