Las Vegas has two types of weather: really hot and cold. There are just a few weeks of ultra-comfortable transitioning weather. Summer starts early and ends late here—it’s not unusual to be wearing shorts on Halloween. Temperatures can reach a scorching 120 degrees, so be prepared with sunscreen and lots of breathable clothing. Heat exhaustion is common, so you also have to drink plenty of water in the heat.
In winters past, Las Vegas has seen more and more snow, though it melts within a day or so and that degree of cold only comes in bursts. If you’re coming from harsh winters, welcome to Heaven, and be prepared to see locals enthusiastically taking pictures and puzzling over the correct application of snow chains. As far as clothes go, you’ll just need a winter coat and sweaters to layer.