Best time to travel to Colorado

Fire Rainbows in Colorado

A curious optical phenomenon occurs quite rarely and only in special locations. If you are in the right time and in the right place, just look up to the sky

Best time: late March–September

Fire Rainbows
Fire Rainbows
Fire Rainbows
Fire Rainbows
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Fire Rainbow or circumhorizontal arc, is a rare optical phenomenon. It is a kind of ice halos formed by the refraction of sun. Actually, it has nothing to do with fire or rainbows, but the way it looks in the sky corresponds to the name exactly.

Rainbow colored flame appears mainly during summer when the sun is at the 58 degrees and higher. There should be a high elevation cirrus cloud with plate-shaped ice crystals. Then, the sunlight has to go through the ice crystals at a particular angle and, as a result, a beautifully colored prism appears in the sky.

The location also matters. Fire rainbows can't be most frequently seen in places north of 55°N or south of 55°S. So Colorado, set between 37°N and 41°N latitude, is not the prime destination for this wondrous natural phenomenon. Yet, there were several reports of such sightings around Denver. In the US circumhorizontal arcs appear occasionally, usually several times a year, from late March till late September.

Practical info

When is the peak season to view fire rainbows in Colorado?

Fire rainbows in Colorado are visible from late March until late September, coinciding with the sun's position at 58 degrees and higher, making it the peak period. Fire rainbows are formed when sunlight passes through high elevation cirrus clouds containing plate-shaped ice crystals, refracting into separate colors, forming a prism, and appearing like a rainbow. However, their occurrence is exceptional, and perfect conditions have to be met, making it a rare sight but still worth the wait. Show more

Can fire rainbows occur anywhere in Colorado?

Fire rainbows may appear anywhere in Colorado, although sightings are rare since specific conditions have to be met. There are reports of sightings around Denver, although sightings are not limited to this location. Colorado's latitude between 37°N and 41°N is not in the prime destination for fire rainbows. Nevertheless, there have been sightings in different attractions such as Breckenridge, Fort Collins, Colorado Springs, and Washington state, making it a stunning natural phenomenon worth experiencing. Show more

What is the process that creates fire rainbows?

Fire rainbows, scientifically known as circumhorizontal arcs, are formed when the sun's light passes through high-level cirrus clouds containing plate-shaped ice crystals. The refraction of the sunlight into different colors forms a prism that appears like a rainbow. To witness a fire rainbow, the sun must be at 58 degrees or higher, and the sun's rays must hit the clouds at a specific angle. Even then, the phenomenon is not guaranteed, making fire rainbows an elusive yet exceptional natural wonder. Show more

Is it a must that cirrus clouds are perfectly aligned to see fire rainbows?

One has to be lucky to see fire rainbows, also known as circumhorizontal arcs, as they are rare. To witness a fire rainbow, high-level cirrus clouds containing plate-shaped ice crystals must allow sunlight to pass through at a specific angle, refracting the sunlight and forming a prism appearing like a fire-colored rainbow. If the alignment of the crystals is not perfect, one may not witness the phenomenon or lack the typical colorful appearance and vibrancy as seen in other sightings. Show more

Are fire rainbows unique to Colorado or exclusive to specific locations?

Fire rainbows are not limited to Colorado and can be seen throughout the world, mainly in areas with high altitude and during summer when the sun is at or above 55 degrees. Sightings have been reported in different states within the United States, including California, Ohio, New Jersey, and West Virginia. Even though it's challenging to predict their appearance and they are rare, the phenomenon is breathtaking and worth experiencing regardless of the location one may be visiting. Show more

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Last updated: by Eleonora Provozin