Weather permitting, as the sun sets the Horsetail Fall waterfall lights up a firefall down El Capitan. Learn about the history and today's natural effect.

February Sunsets Create Firefall at Yosemite's Horsetail Fall Jeongrae Cho

Grab your Nikon and book your ticket to Yosemite--fast!

For two weeks in mid to late February, photographers and tourists from across the world flock to this California national park to witness a stunning celestial illusion. Weather permitting, as the sun sets the Horsetail Fall waterfall is illuminated to the point that the streaming liquid looks like molten lava cascading down the face of El Capitan.

“Horsetail is so uniquely situated that I don’t know of any other waterfall on earth that gets that kind of light,” Michael Frye, who authored, “The Photographer’s Guide to Yosemite,” told the Associated Press.

First captured in 1973 by photographer Galen Rowell, Horsetail Fall sits in a unique position that - with the right geometry, astronomy and physics - when the light is at the lowest optimal angle, the sun’s rays reflect off the granite behind the waterfall and cause this photograph-worthy phenomenon.

For the firefall to happen, several weather conditions need to be right. There needs to be an adequate snow pack to provide water for the waterfall. And then, the temperatures in late February need to be warm enough to melt that snow. The sun will be in the right spot for a couple of weeks in February regardless - there just needs to be a waterfall in place.

For best viewing, head to the El Capitan picnic area.

Old Tradition of "Firefall" with Real Fire

In the late 19th century with James McCauley, owner of a small hotel atop Glacier Point, just one of the enterprising businesses that sprang up during the early days of Yosemite tourism. McCauley's sons, who rode the Four-Mile Trail down to the valley floor to attend school, were told by tourists that they had seen the campfire on Glacier Point the night before. They gave the boys money to pay their father to do it again.

And so began the tradition. The McCauley boys would collect money from tourists after school, then pile firewood on their pack animals, who would carry it back up the cliffs for that night's fire. After hotel guests were finished singing, laughing and sitting around the campfire, McCauley himself would put out the fire by kicking it over Glacier Point. The burning embers looked like a waterfall that had caught on fire. Thus, Yosemite's firefall was born.

Eventually, McCauley sold the hotel at Glacier Point, and the tradition died out for a while. In the early 1900s, the firefall was revived by David Curry, part of the husband-and-wife team who ran the popular Camp Curry in Yosemite Valley. Every night at 9pm, crowds would gather to watch the firefall. A call-and-response would be sounded between Camp Curry and Glacier Point, ending with "Let the fire fall!", after which burning logs would be pushed over the point.

Except for a short hiatus during WWII, the firefall continued uninterrupted until 1968, when NPS Director George Hertzog ended it. Gathering enough dead and downed wood for the nightly event was straining the park's natural resources, and traffic jams in the Yosemite Valley were getting unmanageable. Besides, Hertzog argued, the firefall was an unnatural phenomenon at odds with the park's mission to help people appreciate Yosemite's natural beauty. There are still many long-time Yosemite visitors who fondly remember the firefall, however.

Today visitors can watch a natural "firefall" in Yosemite Valley. Visit during mid- to late February, when the setting sun makes Horsetail Fall near El Capitan appear to be on fire or even look like a river of gold falling down the valley's cliffs 1,570 feet below. Photographers especially won't want to miss this incredible sight.