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Understanding Colorado’s and Pagosa’s climates

To understand the regional and local climates of Colorado, you must begin with a basic knowledge of Colorado’s topography.

Colorado lies astride the highest mountains of the Continental Divide. Nearly rectangular, its north and south boundaries are the 41° and 37° N. parallels, and the east and went boundaries are the 102° and 109° W. meridians. It is eighth in size among the 50 states, with an area of over 104,000 square miles. Although known for its mountains, nearly 40 percent of its area is taken up by the eastern high plains.

Of particular importance to the climate are Colorado’s interior continental location in the middle latitudes, the high elevation of the entire region and the mountains and ranges extending north and south approximately through the middle of the state. With an average altitude of about 6,800 feet above sea level, Colorado is the highest contiguous state in the Union. Roughly three-quarters of the Nation’s land above 10,000 feet altitude lies within its borders. The state has 59 mountains 14,000 feet or higher, and about 830 mountains between 11,000 and 14,000 feet in elevation.

The combination of high elevation and mid latitude interior continent geography results in a cool, dry but invigorating climate. There are large seasonal swings in temperature and large day to night changes. During summer there are hot days in the plains, but these are often relieved by afternoon thundershowers. Mountain regions are nearly always cool. Humidity is generally quite low; this favors rapid evaporation and a relatively comfortable feeling even on hot days. The thin atmosphere allows greater penetration of solar radiation and results in pleasant daytime conditions even during the winter. Outdoor work and recreation can often be carried out in relative comfort year round, but sunburn and skin cancer is a problem due to the intense high-elevation sunlight. At night, temperatures drop quickly, and freezing temperatures are possible in some mountain locations every month of the year.

The climate of local areas is profoundly affected by differences in elevation, and to a lesser degree, by the orientation of mountain ranges and valleys with respect to general air movements. Wide variations occur within short distances. The difference (35 degrees F) in annual mean temperature between Pikes Peak and Las Animas, 90 miles to the southeast, is about the same as that between southern Florida and Iceland.

The annual snowfall at Wolf Creek Pass (elevation 10,850 feet) averages nearly 400 inches and sometimes exceeds 600 inches while at Manassa in the San Luis Valley just east of Wolf Creek Pass annual snowfall is barely 40 inches. Statewide average annual precipitation is 17 inches but ranges from only 7 inches in the middle of the San Luis Valley in south central Colorado to over 60 inches in a few mountain locations. While temperature decreases, and precipitation generally increases with altitude, these patterns are modified by the orientation of mountain slopes with respect to the prevailing winds and by the effect of topographical features in creating local air movements.

Colorado is best known for its mountains. They occupy less of the area of the state than many realize, but they profoundly impact the climate of the entire region. The main feature of the mountainous area of central and western Colorado is the dramatic differences in climate over short distances. With elevations ranging from below 7,000 feet in the lower mountain valleys to more than 14,000 feet on the highest peaks, all aspects of the climate are affected: temperature, humidity, precipitation and, of course, wind.

In general, temperatures decrease with increased elevation. Summer afternoon temperatures consistently decrease about four to five degrees per thousand feet. Typical July afternoon temperatures are in the 70s and 80s in the lower valleys but are only in the 50s and 60s in the higher mountains. But elevational temperature changes are often masked by temperature inversions especially at night and during the winter. Cold air is denser than warmer air and collects in some of the mountain valleys. On clear nights, especially during winter when the ground is snow covered, strong temperature inversions form. Under these circumstances, the coldest temperatures are found near the center of these high valleys, while temperatures in the high mountains are considerably warmer. The San Luis Valley around Alamosa, the Gunnison Valley around Gunnison, the Eagle Valley, the Fraser valley and the Yampa Valley near Steamboat Springs all can be very cold on clear winter nights. Subzero Fahrenheit temperatures are commonplace in these areas and the most winters see at least a few nights with temperatures dropping below -30°F. Even in summer, temperatures can dip below freezing. Under extreme conditions, temperatures have dipped as low as -60 at Taylor Reservoir and -61 along the Yampa valley in northwestern Colorado. Such cold temperatures are rare but demonstrate the extremes that mountain weather patterns can produce. Fortunately, these cold temperatures are nearly always accompanied by light or calm winds.

To help you plan your outdoor adventures, whether you enjoy gardening, camping, horseback riding or cross country skiing, refer to the climactic tables for Pagosa Springs, Colorado.

Table 1: Monthly temperatures for Pagosa Springs. listed, in order, as average extreme high, normal daily high, normal daily low, average extreme low.

January: 51, 38, 3, -17.

February: 57, 44, 9, -10.

March: 64, 50, 18, 0.

April: 72, 58, 24, 11.

May: 79, 68, 31, 20.

June: 88, 78, 37, 28.

July: 90, 83, 45, 36.

August: 88, 80, 45, 36.

September: 84, 73, 37, 25.

October: 75, 63, 26,14.

November: 63, 49, 16, -2.

December: 53, 40, 6, -13.

Table 2: Total monthly precipitation (inches) for Pagosa Springs — normal and maximum.

January: 1.9, 5.3.

February: 1.4, 4.0.

March: 1.8, 4.7.

April: 1.3, 3.8.

May: 1.4, 4.3.

June: 0.9, 2.5.

July: 1.8, 3.8.

August: 2.3, 5.4.

September: 2.2, 5.7.

October: 2.3, 7.8.

November: 1.7, 3.4.

December: 1.5, 3.5.

Table 3: Total monthly snowfall (inches) for Pagosa Springs, normal and maximum:

January: 27.2, 76.0.

February: 18.7, 51.0.

March: 18.0, 47.0.

April: 6.3, 23.0.

May: 1.0, 14.0.

June, July, August, September: 0, 0.

October: 3.1, 16.0.

November: 13.2, 39.4.

December: 20.1, 46.0.

Annual: 105.7, 212.0.

Colorado climate information is provided by the Colorado Climate Center, Colorado State University. Climate tables provided by David E. Whiting, Extension consumer horticulturist, Department of Horticulture and Landscape Architecture, Colorado State University. More information about Colorado’s climate can be found online at www. ccc.atmos.colostate.edu. Colorado State University, U.S. Department of Agriculture and Colorado Counties cooperating. CSU Extension programs are available to all without discrimination.

Anthrax update

There have been two new confirmed cases of anthrax on two additional premises in Logan County. The new cases are located adjacent to the original case announced on Aug. 8, 2012. No other livestock on the newly affected properties are showing clinical signs of the disease.

“This is not an uncommon occurrence with anthrax because adjacent properties may also contain the anthrax spores in the soil; we certainly hoped there wouldn’t be other herds affected but this is the nature of the disease,” said State Veterinarian Dr. Keith Roehr. “We will expand our efforts onto the adjacent premises to protect the health of these cattle. At this time, all of the neighboring herds have been vaccinated for anthrax and affected herds are being treated.”

Anthrax vaccination is an important tool in preventing disease although full protective immunity is not achieved until seven-10 days after a second booster dose is administered.

For information related to the human health risks of anthrax, contact NCHD at (970) 522-3741.

For information related to livestock information, contact the State Veterinarian’s Office at CDA, (303) 239-4161.

Learn more about our upcoming events on our webpage at www.archuleta.colostate.edu<http://www.archuleta.colostate.edu/.

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