I lived in the Southwest and now live in the Detroit area and you definitely get acclaimated a little. Like Eternalhorns said, after winter, when you hit the 50s, its almost tee shirt weather. I tell everyone that anything about 32 is a win. When I've gone back to Nevada to visit family in the early winter, they'd be all bundled up in their winter cloths and maybe I'd have a tee shirt and sweatshirt or light sweater on. I'd laugh at them. OTOH, going back in summer was just painful. The heat that I grew up in was oppressive and I don't think I could take it ever again.
