This is why I love my leather...in every car I drive.
In the summer, if I remember to or feel like it, I put down a drop cover on the seat...the ones that just cover the butt and back portion but don't wrap around. Keeps me from getting burned as hell just sitting on it.
That said, to get " burned as hell" sitting on a leather seat....you'd need direct sunlight with closed windows and 120+ degree temps. I don't put the windows all the way up, always park facing away from the son, and it just doesn't get that hot here in WI.
Winter....well, that's what the heated seats are for. Heck, I use those year round to loosen up my back (especially on long car rides).
For me, no heated leather means no road trip. I'm only 26, but my back is so wrecked that I cannot handle the discomfort of the long drive.