Horsetail Fall transforming into a Firefall in Yosemite National Park (Credit: Scfry/Public domain/ Wikimedia Commons)

Located in California's Sierra Nevada mountains, Yosemite National Park is famous for its giant, ancient sequoia trees and impressive rock formations, like El Capitan and Half Dome. However, from mid-to-late February each year, the pristine preserve's main attraction is Horsetail Fall — a temporary waterfall that flows over the eastern edge of El Capitan every winter. During the brief two-week-period, the 1,500-foot-tall waterfall frequently transforms into a spectacular natural Firefall.

For the natural phenomenon to occur, many conditions have to be perfectly aligned. For starters, there must be adequate snow, and the temperatures have to be warm enough for it to melt and form the temporary waterfall. During dry, or exceptionally cold, years, Horsetail Fall is reduced to a trickle, or fails to form altogether. The skies also have to be completely clear and cloudless, since even a slight haze can ruin the illusion of fire tumbling down the cliffs. Most importantly, the sun has to strike the water at a certain angle to light up the upper part of the falls, creating the distinctive, deep orange glow, reminiscent of a lava flow. Even if all the conditions are met, the wondrous spectacle, which occurs about 5 to 15 minutes before sunset, lasts just a few minutes.

Even with perfect conditions, the stunning Firefall only appears for a few minutes each day ((Credit: Ambitious Wench - originally posted to Flickr as P2160903.jpg/ CC BY-SA 2.0,/

The Yosemite Firefall has been popular with both professional and amateur photographers since the 1940s. However, thanks to social media, its fame has risen to new heights in the past few years. Things came to a head on February 22, 2019, when a record 2,200 people crammed into the small viewing areas to observe the light show. In their quest to get a glimpse of the fleeting natural phenomenon, the visitors spilled onto riverbanks and trampled over sensitive vegetation. They also left behind large amounts of trash.

To prevent a repeat of the unfortunate incident, every February, park officials close off the paths to the two easily accessible viewing areas. Visitors hoping to catch a glimpse of the Firefall now have to park in designated lots and hike 1.5 miles (each way) to get to the only open viewing spot. This year, to ensure COVID-19 social-distancing protocols are observed, visitors will require a reservation to enter the park from February 8 to February 28, 2021, reducing the crowds even further.