Colorado weather is influenced by its latitude, topography, elevation, distance from large bodies of water and the jet streams. Lower elevations are generally mild, but given to vast extremes of hot and cold. Violent weather, even deadly weather, can strike anywhere in the state at virtually any time. Global trends and factors have their influence, but local factors can rapidly change conditions. Even a short drive across the Rocky Mountains from the plains to the canyons might render a variety of different weather conditions, sometimes only a few miles, or minutes, apart.
Latitude affects the sun’s position in the sky and therefore hours of daylight and the angle and intensity of the rays as they strike earth. Between 37 and 41 degrees north latitude, Colorado receives between 9 and 15 hours of daylight. Predominant winds also are influenced by latitude. Colorado weather is greatly affected by westerly winds that bring storms from the Pacific Ocean inward. Jet streams to the north and south can shift position, affecting storm paths and weather conditions.
At nearly 1,000 miles from the Pacific Ocean, Colorado weather is not heavily influenced by any adjacent large body of water, nor does the atmosphere carry much humidity. Storms moving in from the Pacific often lose much of their moisture to mountain ranges encountered along the way. The state’s average humidty is 38%.
Temperatures and atmospheric pressures decrease with increasing altitude. Temperatures drop between 3.3 and 3.6 degrees F for every 1,000 feet in altitude gained. Atmospheric pressures will range from 24 inches of mercury to under 20 inches of mercury. Air masses moving west to east must rise over the mountains or significant upthrusts such as the Colorado Plateau. As the air rises, it cools. The cooler the air, the less moisture it cancarry. The result is significantly more snow and rain on the Western Slope of the Rocky Mountains compared to the eastern plains. Precipitation can vary by more than 300% from protected leeside valleys to windward mountain peaks.
Any area 9,000 feet or higher will experience a very short growing season. Frost can occur any day of the year at 9,000 feet. Fraser, in the upper reaches of Middle Park, is credited with having the shortest growing season in the state with an average of 48 frost-free days a year. Fruita, near the Utah border in the Grand Valley, enjoys one of the state’s longest growing seasons.
Dense cold air often will settle in the low points of high mountain valleys causing extreme low overnight temperatures.
A winter phenomenon known as chinook winds can blow down off the mountains to the eastern plains to warm winter days. Rapid temperature increases of 25 to 30 degrees are not uncommon.
Higher elevations are analagous to northern latitudes. In a 20-mile drive from the Great Plains to the summit of Pikes Peak, one passes through four separate ecosystems – Grassland, Montane Forest, Subalpine Forest and Alpine Tundra. To pass through similar life zones without gaining altitude, one would have to drive as far north as Northern Alaska. Many of the plants and animals living in Colorado between 9,000 and 11,500 feet, in the spruce-fir forest life-zones, thrive at 1,000 feet in northern Canada. The low tundra vegetation above timberline in Colorado (approx. 11,000 feet) is similar to plant life found in the Arctic tundra. The 35-degree difference in annual mean temperature between the summit of Pikes Peak and Las Animas, 90 miles southeast, is comparable to the difference between south Florida and Iceland.
Highly varied topography results in highly varied micro-climates. Differences in slope, elevation and aspect impact the amount of solar heating from one point to the next. Steep slopes create shaded valleys, while any slope with a northern aspect gets only minimal sun all winter. Conversely, south-facing slopes soak up the sun’s heat. They are warmer and drier than other areas and therefore will feature different vegetation.
Because of the varied terrain and altitude of the state, it is impossible to summarize Colorado’s weather. Instead, we have included weather summaries from various points across the state. The points were selected from the more than 130 weather stations across the state to represent major geographical regions, various elevations and population centers.
Colorado Extreme Weather Records
Source: Western Regional Climate Center
Record high temperature:
118ºF on July 11, 1888 in Bennett, Colo.
Record low temperature:
-61ºF on Feb. 1, 1985 in Maybell, Colo.
Highest average annual temperature:
56.4ºF at Eversoll Ranch in Baca County.
Lowest average annual temperature:
29.2ºF at the summit of Berthoud Pass.
Most consecutive days with high temperature of 90ºF or greater:
76 days from June through September 1983 in Las Animas, Colo.
Most consescutive days with low temperature of 32ºF or lower:
310 days from Aug. 1985 to June 1986 in Taylor Park near Gunnison, Colo.
Record maximum annual precipitation:
92.84 inches in 1897 in Ruby, Colo.
Record minimum annual precipitation:
1.69 inches in 1939 in Buena Vista, Colo.
Record maximum 24-hour precipitation:
11.08 inches on June 17, 1965 in Holly, Colo.
Highest average annual precipitation:
45.35 inches at the summit of Wolf Creek Pass.
Lowest average annual precipitation:
7.05 in Center, Colo. in the San Luis Valley.
Most consecutive days with measurable precipitation:
45 days from November 1983 to January 1984 at the summit of Berthoud Pass.
Most consecutive days with no measurable precipitation:
156 days from October 1936 through March 1937 in Haswell.
Record maximum winter snowfall:
807 inches in 1978-1979 at the summit of Wolf Creek Pass.
Record maximum 1-day snowfall:
75.8 inches April 14-15, 1921 at Silver Lake, Colo.
Highest average annual snowfall:
434.8 inches at the summit of Wolf Creek Pass.
