When it comes to the great state of Colorado, it seems 300 is the magic number. Colorado receives over 300 inches of snow annually at various mountain resorts, and according to some sources, the state sees 300 days of sunshine annually. Is this true?

Some suggest the "300 days of sunshine" claim is simply a marketing ploy. Then again, one has to wonder what constitutes a "sunny day."

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Who Says Colorado Gets 300 Days of Sunshine?

It might be best to start by determining who's behind the claim Colorado enjoys 300 days of sunshine. The opening line at Colorado.com reads, "With 300 days of annual sunshine, mild temperatures and record snowfalls, there’s never a bad time to come to Colorado."

The Denver Post reports Colorado's claim of 300 days of sunshine dates clear back to the 1870s, originating with a publicist for a railroad company.

Making the Distinction Between "Sunny" and "Partly Sunny"

If the sun comes out for an hour in Colorado, have we experienced a "sunny" day? What is the working definition of a sunny day in Colorado? According to 4 CBS Denver, In Colorado, there are three locations that operate a device called a “sunshine switch” that measures sunlight by the minute. These sunshine switches are located in:

  • Colorado Springs
  • Denver
  • Pueblo

4 CBS Denver adds the Colorado Climate Center did a study in the 1990s based on sunshine switch data. That study found that where Denver is concerned if you count every day when the sun came out for at least one hour, you would arrive at an average of around 300 “days of sunshine” annually.

A Matter of Opinion

I don't know about you, but I wouldn't exactly consider one hour of sunshine to be a "sunny day." You can probably recall rainy days in Colorado where the sun made an appearance for an hour or so.

As it turns out, the National Weather Service has a criteria for determining if a day is clear, cloudy or partly cloudy. The breakdown is:

  • Cloud cover each day is 30% or less = clear day
  • Cloud cover is 80% or more = cloudy day
  • Anything falling between a clear day and a cloudy day = partly cloudy day

If we work with these definitions from the National Weather Service, then the Colorado Climate Center study mentioned above finds Denver, Colorado typically experiences:

  • 115 clear days annually
  • 130 partly cloudy days annually
  • 120 cloudy days annually

Not Exactly The Stuff Great Ad Campaigns Are Made Of

It goes without saying these numbers don't exactly lend themselves well to an effective marketing campaign for Colorado. Imagine the state's tourism board attempting to launch a campaign stating, "Come to Colorado and enjoy130 partly cloudy days." How about, "Come to Colorado and enjoy 115 clear days each year based on the findings of the National Weather Service and a Colorado Climate Center Study."

There's a Story That Goes With This

The claim of "300 Days of Sunshine" sound good to the ear. I don't believe the publicist behind the statement meant to mislead anyone. Obviously, Colorado is not the state of Washington with rain 183.7 days of the year. We do get sun, and sometimes, weeks and months of uninterrupted sunshine. In all reality, though, with the endless list of attractions offered by Colorado, "sunshine" isn't exactly a selling point for the state.

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