Las Vegas hosts 3 festivals in this guide, in Nevada: Electric Daisy Carnival Las Vegas, Life is Beautiful, When We Were Young.
Las Vegas has 3 festivals in this guide. They run in May, September and October, and festival-day temperatures range from 26°C (79°F) to 33°C (91°F), with nights down to 14°C (57°F). That range is the reason there is no single "Las Vegas festival outfit". The answer changes by month and by site.
2 of them run in real heat (28°C or more), where loose natural fabrics beat coverage and a brimmed hat does more than any garment.
The ground matters as much as the sky. You will find arena grounds and city streets, which puts broken-in trainers or a low boot at the top of the list for most of these events. 1 of the 3 has camping on site, so outfits have to survive living in a bag on the ground for several days.
Stylistically the crowd here leans y2k, rave, edm and neon. Electric Daisy Carnival Las Vegas is the largest of them at around 170,000 people, and it sets the tone the smaller ones react to. None of that is a dress code. It is what you will see, which is worth knowing if you would rather blend in or deliberately not.
