Horsetail Fall flows over the eastern edge of El Capitan in Yosemite Valley. This small waterfall usually flows only during winter. On rare occasions during mid-to late February, it can glow orange when it’s backlit by sunset. Seeing it is a once-in-a-lifetime experience. Many factors have to align. The right amount of water, sun, shadow, wind.
Old Bat Firefall is more reliable. All it needs is sunset. It also shows up in February.
If you are curious, here is a little 8-minute video about Horseshoe Falls Firefall and some vintage film about the original Glacier Point Firefall. When the NPS actually pushed glowing embers off a cliff. Every night. To amuse the visitors.