The high country of Rocky Mountain National Park is noted for extreme weather patterns. Shaped by elevation, slope, and exposure, these patterns can change rapidly.

Temperatures are often moderate at elevations below 9,400′ (2,865 m). At higher points, like Bear Lake, Trail Ridge Road, or Longs Peak, it may snow even in July.

A wide variation between day and nighttime temperatures is also typical of mountain weather.

Summer days in July and August often reach the 70’s or 80’s and drop into the 40’s at night. All temperatures given are in Fahrenheit.

Based on ten years of precipitation data, Estes Park receives approximately 13.10″ of moisture every year. Grand Lake receives about 19.95″ yearly. This precipitation comes in the form of rain or snowfall through the year.

Climate and Weather – What’s the Difference?
Climate is a general term to express broad patterns. For example, Colorado’s climate is sunny with warm summers and cold winters. Weather applies to specific movements of air masses, levels of precipitation, and temperature fluctuations at specific times of the year. The Continental Divide runs northwest to southeast through the center of the park atop the high peaks. This accounts for two distinct climate patterns – one typical of the east side near Estes Park and the other associated with the Grand Lake area on the park’s west side. In recent years, park researchers have been tracking changes to the climate in the park.

Winter (December – March) 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 clear cold days during these months. Most high country overnight trips require gear suitable for -35 degrees or below. Skiing and snowshoeing conditions are best in January, February, and March.

Spring (April – May) Spring comes to the montane area – elevations 8,000′ to 9,500′ (2,438 – 2,895 m) – in late April, although snowfall is not uncommon at this time of year. Unpredictable weather alternates between warm and cold, wet and dry. In June, spring is just reaching the subalpine country – 9,500′ to 11,500′ (2,895 – 3,505 m), while summer is on the plains. Wildflowers begin blooming at lower elevations in late April or early May. Many trails are still snow-covered. In late May, Trail Ridge Road opens for the season.

Summer (June – August) On the alpine tundra — 11,500′ to 13,000′ (3,505 – 3,962 m) wildflowers bloom from late June to early August. Afternoon thunderstorms and wind are normal patterns. Always be prepared for temperature drops of 10-20 degrees Fahrenheit.

Fall (September – November) September and October bring clear, crisp air, blue skies, and generally dry weather. An early snowstorm may occur. Aspen leaves start changing colors in mid-September. Elk mating season begins in September and continues through most of October. Trail Ridge Road usually closes for the winter by mid-October.

Estes Park is a town in Larimer County, Colorado, United States. A popular summer resort and the location of the headquarters for Rocky Mountain National Park, Estes Park lies along the Big Thompson River. Estes Park had a population of 5,858 at the 2010 census. Estes Park sits at an elevation of 7,522 feet (2,293 m) on the front range of the Rocky Mountains at the eastern entrance of the Rocky Mountain National Park. Its location is 40°22?22?N 105°31?09?W. Its north, south and east extremities border the Roosevelt National Forest. Lumpy Ridge lies immediately north of Estes Park.

According to the United States Census Bureau, the town has a total area of 5.9 square miles (15 km2), of which 5.8 square miles (15 km2) is land and 0.1 square miles (0.26 km2) (0.85%) is water.

Three million tourists visit Rocky Mountain National Park each year; most use Estes Park as their base.

Rocky Mountain National Park is a national park located in the Front Range of the Rocky Mountains, in the north-central region of the U.S. state of Colorado. It features majestic mountain views, mountain lakes, a variety of wildlife, varied climates and environments—from wooded forests to mountain tundra—and easy access to back-country trails and campsites. The park is located northwest of Boulder, Colorado, and includes the Continental Divide and the headwaters of the Colorado River.

The park has five visitor centers. The park headquarters, Beaver Meadows Visitor Center, is a National Historic Landmark, designed by the Frank Lloyd Wright School of Architecture at Taliesin West.

The park may be accessed by three roads: U.S. Highway 34, 36, and State Highway 7. Highway 7 enters the park for less than a mile, where it provides access to the Lily Lake Visitor Center which is closed indefinitely. Farther south, spurs from route 7 lead to campgrounds and trail heads around Longs Peak and Wild Basin. Highway 36 enters the park on the east side, where it terminates after a few miles at Highway 34. Highway 34, known as Trail Ridge Road through the park, runs from the town of Estes Park on the east to Grand Lake on the southwest. The road reaches an elevation of 12,183 feet (3,713 m), and is closed by snow in winter.

The California Zephyr serves Granby (near the west entrance of the park) by rail from Denver, crossing the Continental Divide through the Moffat Tunnel well south of the park. The park’s website suggests Granby as an appropriate rail terminus for visitors, although it lies about sixteen miles from the park without public transportation connections.

The park is surrounded by Roosevelt National Forest on the north and east, Routt National Forest on the northwest, and Arapaho National Forest on the southwest.