Denver’s official temperature along with all other weather information including snowfall is recorded at DIA because commercial airports are the origin of regular weather observations in the United States. This is mandated by the National Weather Service and the Federal Aviation Administration. 
The official weather observation location has actually been moved multiple times since 1871 resulting in an incongruous climate history for Denver. Weather observations were originally recorded downtown, first near the corner of Larimer & 16th Streets and then at the Post Office building at 19th & Stout Streets. In 1950 the official observation station was relocated to Stapleton Airport before being moved to DIA in 1995.
9NEWS is not involved in the process of determining the location of official weather observation stations.

The only official snowfall measurement for the Denver area is recorded at DIA on the southeast side of the airport. This measurement is recorded daily at midnight using an automated system. All other snowfall measurements around the metro area are considered "unofficial". Until 2008, the official snow measurement for Denver was recorded at the former Stapleton Airport site.

The climate section on the Denver National Weather Service website offers historical weather data for Denver going back five years. Click here and then click on “Preliminary Climatology Data (CF6)” to find daily information about temperature, precipitation, snowfall, wind speed, etc.

For historical weather data beyond five years ago or for locations other then Denver, visit the National Climatic Data Center website or call them at (828) 271-4800. The NCDC may charge a fee for their data.

For detailed precipitation records for hundreds of locations throughout Colorado, visit the Community Collaborative Rain, Hail and Snow Network (CoCoRaHS) website.

You may also be able to obtain information from the Colorado Climate Center at Colorado State University in Fort Collins.

Regardless of what you may hear, each year Denver averages 115 mostly sunny days, 130 partly cloudy days, and 120 mostly cloudy or cloudy days. If you consider partly cloudy days to be “sunny”, then Denver averages 235 days of sunshine each year. The popular claim of 300 days of sunshine each year in Denver is only true if every day with at least some sunshine is considered a “sunny” day.

Heat produced by the human body radiates out of our skin and into the surrounding air. When there is no wind, this thin layer of heat partially insulates us from the full effect of the cold surrounding us. When conditions are windy, this layer of heat is swept away from the body and thus the full impact of the cold air is felt on our skin. Even though the actual air temperature is the same when conditions are windy, it "feels" colder. The wind chill temperature gives a comparison to what it would feel like at a lower temperature if there were no wind. Wind chill only applies humans and other living things; it has no effect on objects such as vehicles. Click here for more information.

9NEWS does not have direct control over any tornado or severe weather sirens. They are typically activated by city or county officials, usually a police or fire department or emergency management personnel. Some officials wait for the National Weather Service to issue a tornado warning, while others wait until a tornado has been identified by spotters.

Our partners at the USA TODAY have developed a website with links to a wide variety of weather related material especially for teachers. Click here.

NOAA and the National Weather Service have also published a comprehensive website to help students, teachers, librarians and the general public access resouces for learning about the enviorment. Click here.

When the atmospheric pressure is above 1013.25 millibars (the equivalent of 29.92 inches of mercury), we are considered to be under high pressure. This implies that the atmosphere is "denser" and therefore air tends to sink. Winds flow in a clockwise motion around the center of high pressure. Sinking air under an area of high pressure generally means a lack of cloud cover, precipitation, and wind. During the summer months, temperatures are usually very warm with high pressure while the opposite is true in the winter.

When the atmospheric pressure is below 1013.25 millibars (the equivalent of 29.92 inches of mercury), an area is considered to be under low pressure. This implies that the atmosphere is "less dense" and therefore air tends to rise. Winds flow in a counter-clockwise motion around the center of low pressure. Since the air is rising under an area of low pressure, it cools and condenses generally causing clouds and possibly precipitation.

When skies are clear and winds are light or calm, the heat accumulated during the day rapidly rises, or radiates upwards. This results in a quick drop in temperatures shortly after sunset.

They essentially mean the same thing.  Partly Cloudy can be used during the day or night, while Partly Sunny obviously is only used during daylight hours. They are both supposed to represent sky conditions where between 32% and 69% of the sky is predominately covered by clouds. This is more of a generalization for the time period in question, and does not mean that skies couldn’t be nearly clear or totally cloudy for brief periods.

Forecasts on 9NEWS will often include both of these terms. Scattered is a more common occurrence than isolated. In other words, you are more likely to see rain or snow when there is a chance of "scattered showers" than when there is a chance of "isolated showers".

A “Chinook” or “downsloping” wind refers to a westerly wind that descends the leeward side of a mountain range. As Chinook winds force an air mass down the east slope of the Front Range Mountains, the air mass encounters stronger atmospheric pressure causing it to warm. This generally results in gusty winds causing warm, dry conditions for the Denver area. Chinook winds where named after the Chinookan Indians who lived in present day Oregon and Washington since the wind came from that direction. Chinook winds occur all along the Front Range of the Rocky Mountains from Alberta, Canada to Albuquerque, New Mexico.

9NEWS Meteorologists will often use the term “upslope” during weathercasts as an easy way to refer to “orographic lift”. Orographic lifting occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. This occurs frequently in Colorado when an easterly wind is present over the Eastern Plains. As an air mass moves west it encounters the mountains it is forced upward. As the air gains altitude, it expands and cools. Cold air can’t hold moisture as well as warm air and therefore moisture contained within the air is forced out through a process called “condensation” which changes invisible water vapor into a liquid. As the air condenses, it creates clouds and often precipitation. The process can bring significant snow to Denver in the winter and heavy rain in the summer.

We recommend you use the Career Guide published by the American Meteorological Society. A list of colleges and universities that offer courses in meteorology, atmospheric science and weather forecasting can be also found here.

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