Every February, Yosemite's Horsetail Fall turns into a Firefall (Credit: Visitcalifornia.com/ CC-BY-SA-2.0)

California's Yosemite National Park is famous for its giant, ancient sequoia trees and impressive rock formations. They include El Capitan and Half Dome. But from mid to late February, the park's main attraction is Horsetail Fall, located at the edge of the eastern side of El Capitan. During this time, the setting Sun hits the seasonal waterfall at just the right angle, creating the illusion that it is on fire.

In 2024, the natural phenomenon known as the "Firefall" is estimated to happen between February 9 to 25. But there is no guarantee it will occur.

Many conditions have to be met for the Firefall to occur (Credit: Scfry/ Public Domain/ Commons.wikimedia.org)

For the Firefall to occur, certain conditions need to be met. For starters, there must be enough snow. Also, the temperature has to be warm enough for the snow to melt and flow down the rock's edge. During dry or exceptionally cold years, Horsetail Fall is reduced to a trickle or fails to form altogether.

But even a robust waterfall does not guarantee a Firefall. The skies also have to be clear and cloudless. Even a slight haze can ruin the illusion of fire tumbling down the cliff. Most importantly, the Sun has to strike the water on the upper part of the fall at a certain angle. This helps create a distinctive, deep orange glow reminiscent of a lava flow. Even if it all comes together, the remarkable spectacle lasts about three minutes.

Left: Overcrowded riverbanks damaged sensitive vegetation in 2019. Right: A section of riverbank collapsed under stress from spectators (Credit: NPS.gov/ Public Domain)

Photographers have known about the Firefall since the 1970s. However, its popularity has recently risen due to social media. On February 22, 2019, over 2,200 people crowded into the small viewing areas to see the fleeting light show. Many visitors spilled onto riverbanks and walked over sensitive vegetation. They also left behind a large amount of trash.

Since then, the two easily accessible viewing areas have been closed to visitors every February. The natural phenomenon can now only be seen by hiking 1.5 miles (2.4 km) each way. Furthermore, reservations are required for park entry during the last three weekends of the month.

Resources: NPS.gov, Yosemite.com