The flight lasts many hours, from mid-morning until sundown, which would be between 8 and 9 pm, depending on where the lake was located. It isn’t a pleasant flight.
On and on they flew, over countryside parceled out in patches of green and brown, over roads and rivers winding through the landscape like strips of matte and glossy ribbon…[Harry’s] hands were numb with cold but he did not date attempt to shift his grip. He had been wondering for some time what they would do if they saw the coast sail beneath them, if the dragon headed for open sea. He was cold and numb, not to mention desperately hungry and thirsty. When, he wondered, had the beast itself last eaten? Surely it would need sustenance before long? And what if, at that point, it realized it had three highly edible humans sitting on its back? The sun slipped lower in the sky, which was turning indigo; and still the dragon flew, cities and towns gliding out of sight beneath them, its enormous shadow sliding over the earth like a giant dark cloud. Every part of Harry ached with the effort of holding on to the dragon’s back. (DH26)