Heck you barely need to step outside in Vegas. I've been there multiple times and the temperature could have been 60 or 120 and I doubt anyone around me would have known the difference.
I was there for Google Next in April and it was hovering between 95 and 100 and I was comfortable in jeans and a polo, but I would have been just as comfortable at 60.
Living in the Upper Midwest, I find it so interesting that we deal with -40F to >105F (sometimes with 80 degree temperature swings in a day or two; going from -40 to +40) just fine but folks in places like Los Angeles, Las Vegas, and Tampa, FL cannot seem to handle even 10 degree swings. Crazy.