by Kathleen Spring

Created on: January 25, 2010   Last Updated: March 25, 2010

If a person watched the national weather report, they might see snow falling in the Rocky Mountains of Colorado that could be measured by the foot, and yet Denver might be sunny and 60 degrees. Colorado is one of those fluky states that can experience noticeably different climate on the same day, or by driving 100 miles in the opposite direction.

A closer look at the map would reveal that the mountains run down the middle and western portion of the state. The eastern half of the state consists of semi-arid, high plains and grassland. The lower southeast part of the state is considered high desert. The most populated area is the Front Range urban corridor, which is a collection of towns on the eastern slope of the Rocky Mountains.

One thing that is consistent across Colorado is the big blue sky and open spaces. A person can often see a change in the weather in a town 80 miles away, whether it is a black sky from a thunder storm, or a brown sky from a dust storm.

Add 300 days of sunshine to this. The high altitude, whether in the 14,000 foot mountains or the 3,300 foot plains, brings more direct sun for people to enjoy. The sunny open skies in the high altitude have two advantages. First, in the winter, the closer sun melts the snow quickly. The Front Range can have a snow fall of 10 inches, and it can be completely melted in a day or two. Second, on the hottest days of summer, residents can look forward to nights a natural 30 degrees cooler than the daytime Once the sun sets, the heat rises into the clear mountain sky.

Vacationers can find good climate in Colorado year round, with moderate but distinct summers and winters. Even in winter, residents often do not need a cap, gloves, or boots. The low humidity prevents the “chilled to the bone” feeling in winter, and the “dripping sweat” of summer.

There are a few extreme climate problems. The fierce winds in Colorado can reach 70 to 90 mph. There are sporadic tornadoes on the eastern flatter side of the state. Rare strong winds, known as Chinooks, come up the mountains from the south and carry warmer air which causes storms, and sometimes avalanches. Arctic winds can bring unusually cold air down to Colorado.

The mountains not only influence the strength of the sun on Colorado, but they also affect rainfall.  The mountains block passage of rainfall on the eastern slopes, which averages 15 to 17 inches per year compared to 40 inches of rain on the western slope. This climate affects the farming methods and increases forest fires. The snow melts in the mountains in spring cause the Colorado rivers to often rise to near flood levels.

Colorado's coldest weather of the winter peaks in January, with temperatures averaging 41 degrees, and lows near 20. March and April have some of the heaviest snowfalls, often 13 inches in town and at least double that in the mountains. But expect several days in the 50s. Spring starts slowly in May, with an average temperature of 70 degrees. It is also the wettest month with two and a half inches of rain and often cloudy.

Summer begins with June, the greenest month. July can occasionally reach 90 degrees during the day, and 65 to 70 at night. August can be hot, but the days are starting to cool down. The aspens begin to turn golden in late September and early October. The fall is often picked as the prettiest time of the year. The first snowfall usually occurs in October. November has increased snow and less sun, beginning the winter hibernation period.

National Weather Service Forecast Office offers specific details.

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