If you are planning a trip to Las Vegas that is going to include a trip to several national parks while you are here, you may be wondering about the weather in those places during the day as well as overnight. If you are going to be camping outside overnight in the parks, will you need to dress for colder temperatures, or will it be staying warm? If you are going to be hiking in the parks during the days, are you going to be overheated if you are wearing certain clothes? Will you get sunburned if you do not wear long sleeves? Will you need to wear a hat? All of these are legitimate questions and concerns that many visitors have.
It is important to understand that the temperatures that you will be experiencing in Las Vegas on the morning that you are leaving for your trip are probably not going to be the temperatures in the parks, and the overnight temperatures are probably going to be significantly colder. On a typical summer day in Las Vegas, you would probably not want to be outside hiking due to the excessive heat between June and September. Temperatures during these times can easily go over 110 degrees, and at night might only go down to 100 degrees. On these days, most people in Las Vegas are staying inside in the air conditioning, but during this exact same time people are hiking in Zion Canyon in perfect weather. On a 110 degree day in Las Vegas, the temperature in Zion will usually be around 8 degrees, and in Bryce it will be even cooler at about 82 degrees. On that exact same day the Grand Canyon might be more like Las Vegas, with temperatures about 105 degrees or so. These variations in temperature are going to force you to plan for anything, due to the fact that camping outside in these places might see the temperatures going as low as the high fifties. During this same trip you may need a sweatshirt and short sleeves, with potential temperatures between day and night varying almost 30 degrees. You must remember that not only are you not used to these temperatures, you are also probably not used to being outside all day, or sleeping outside overnight. Most people are used to a more climate controlled environment where the temperatures are consistent between day and night, due to the fact that their thermostat regulates the temperature through out the day.
When you take your trip to the parks in the southwest, it is best to think of it as Las Vegas probably being much hotter than the parks will be both at nigh and during the day. You will find that the parks will seem like a reprieve from the desert heat, probably because they are! When you see the green plants and foliage of areas like Zion and compare it to the natural topography of Las Vegas, it becomes clear that the city is in a more harsh desert climate than the parks are. Dress for it!