Yosemite's 'firefall': Fiery-red water looks like lava

Sunset lights up Horsetail Falls in California's Yosemite National Park for a few days every year

An annual trick of the light is treating visitors to a fiery red waterfall at California's Yosemite National Park.

The setting sun lights up Horsetail Falls for a few weeks every February in a phenomenon called a "firefall".

When conditions are just right, the waterfall looks like lava gushing thousands of feet from a high cliff.

The spectacle lasts only a few minutes a day, but attracts hundreds of visitors to the park every year.

Haze or even slight cloudiness can diminish or eliminate the effect, the National Park Service says. But "when the sun drops at the exact right angle," spokesman Scott Gediman tells AFP, "it's magical".

California and much of the western US has been plagued by drought for years, threatening the firefall's appearance.

But the downpours and massive flooding that devastated much of the west early this year have plumped up the state's watercourses, making this year's firefall picture-perfect.

Wednesday's freezing temperatures did not deter park visitors, who either sat, knelt or stood atop sheets of ice with cameras in their hands.

"The pictures I've seen are just gorgeous," amateur photographer Terry Cantrell told CBS News, the BBC's US partner. "Everybody wants to have their own, so this is what I'm trying to do."

But not everybody gets see the firefall, even when conditions are just right. The National Park Service limits visitors through a reservation system in order to protect the natural surroundings.

Haze or even slight cloudiness can diminish or eliminate the effect

Visitors gather to see the so-called firefall at Horsetail Falls in Yosemite National Park this week