LARIMER COUNTY, Colo. (KDVR) — America’s highest continuous paved road opened for the season Friday, according to the National Park Service.

Trail Ridge Road spans Larimer and Grand Counties, climbing to 12,183 feet, cutting through the heart of Rocky Mountain National Park. While crews have been working hard to clear the road ahead of Memorial Day weekend, conditions may have the park shut it down once more.

“Because weather conditions may change rapidly, and winter weather is forecast for higher elevations this holiday weekend, including freezing temperatures and some snow accumulation, park visitors should be prepared to adjust travel plans accordingly and are encouraged to call the park’s Trail Ridge Road recorded status phone line at (970) 586-1222,” a spokesperson for park services said in a statement.

Timed entry permit reservations also go into effect Friday, to continue to portion the massive flow of visitors to one of the most popular national parks in the country.

There are two types of reservations parkgoers can grab: Bear Lake Road Corridor, and the rest of Rocky Mountain National Park, which includes Trail Ridge Road. The Bear Lake reservation period spans from 5 a.m. to 6 p.m. while the other permit runs from 9 a.m. to 3 p.m.