Lower elevations on the east slope of Rocky Mountain National Park are usually free of deep snow. At higher elevations arctic conditions prevail. Sudden blizzards, high winds, and deep snowpack are common. The west side of the park experiences more snow, less wind, and sunny but cold days during these months. In June, spring is just reaching the subalpine country - 9,500' to 11,500', while summer is on the plains.
Many trails are still snow-covered.
In late May, Trail Ridge Road opens for the season. Afternoon thunderstorms are a normal pattern. Be prepared for temperature drops of 10-20 degrees. September and October bring clear, crisp air, blue skies, and generally dry weather. An early snowstorm may occur.