This event can happen every year around the 3ed week in February in Yosemite National Park. The waterfall is called Horsetail falls and flows off the granite monolith, “El Capitan”. Since the waterfall depends on the rain and snow melt from the top of El Capitan, the waterfall is not flowing all year long. The Firefall effect can only occur when the sunset is at just the right angle. There also has to be a colorful sunset with no clouds on the horizon. There is no guarantee this will happen every night or even every year. All of the conditions have to be just right.