A massive heat dome covering more than half of the United States is subjecting millions of people to some of the highest summer temperatures in more than a decade. Thick humidity is making matters even worse, with “sensible” conditions likely to exceed 110 degrees Fahrenheit in many areas. At least one region of the country is experiencing a brief respite from this scorching summer. Earlier this week, visitors to Yellowstone National Park saw a blanket of fresh snow covering their trees and streams.

“It may be almost July, but that doesn’t stop snowstorms from occasionally occurring in Yellowstone,” officials wrote in a social media post.

As magical as some parts of the park may seem, the explanation behind the snowy views is not the magic of the weather. Icy conditions can appear seemingly out of nowhere in Yellowstone due to its elevation. Most of the park sits at least 6,000 feet above sea level, meaning it often has much colder temperatures than other parts of the country. By comparison, the average elevation within the US is only about 2,500 feet.

Summer highs in Yellowstone hover around 70 and 80 degrees, but those numbers often plummet at night. The nights are “normally cool”, but in higher altitude areas sub-zero temperatures are sometimes still recorded. Thanks to the season’s frequent afternoon storms, those downpours can easily turn into sleet and snow.

Although icy conditions may be temporary, the latest example is a great reminder to always prepare accordingly before visiting national parks, especially Yellowstone.

“No matter where you visit, bring a warm jacket, rain gear and plenty of layers,” park officials suggested.

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