Yosemite’s moonbows are rare, nocturnal phenomena. Here’s how to see one.

As midnight nears, the roads circling Yosemite Valley appear all but abandoned. Car headlights freeze a mule deer crossing the roadway. A coyote limps by, nursing a foreleg. To the south, dark, hulking outlines hint at the sheer walls encasing the valley of California’s most iconic national park. But to the north, from El Capitan to beyond Yosemite Falls, gray granite faces are awash in warm moonlight. The glow beckons us.

A knot of onlookers has gathered at the falls’ roaring base, phones and cameras at the ready. They are searchers, drawn by the full moon’s promise of revealing moonbows, a rare, nocturnal version of rainbows. Yosemite National Park brims with wonders in any season, and for a few months each year, moonbows rise with them.

Yosemite remains one of Earth’s few places where nature consistently conjures moonbows. The park is blessed with plentiful waterfalls, including one of North America’s tallest. Peak moonbow season follows the lunar cycle from spring to mid-summer, but a relatively dry winter and early snowmelt mean the last predictable opportunity for 2026 could be May 28 through June 3.

I know this because I am a moonbow hunter. Like me, many others following headlamps toward the sound of falling water this April are neophytes. Through a shared interest and expertise, we rely on others to predict this dazzling dance between lunar light and water.

For the second time in the last three years, Brian Hawkins has agreed to traipse around the park with me. He didn’t originate the practice, but since 2018 he has posted Yosemite moonbow predictions online.

Overcast skies plagued the last trip, but tonight the moon shines brightly, stalking our steps on the approach to Lower Yosemite Fall. As the waterfall’s roar intensifies, Hawkins flicks me a question: “Are you ready to see a moonbow?”

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Muir’s lunar rainbows

Naturalist John Muir, who introduced Yosemite to the world in the 19th century, characterized the full moon’s effect on waterfalls as lunar rainbows, or spray-bows.

Much like the aurora borealis, moonbows to the naked eye usually appear shrouded in shades of gray and white. That’s because of how our eyes’ sensors function: activated in low light, photoreceptors called rods fail to instantaneously distinguish colors. Modern digital cameras, however, gather enough light through longer exposures to record vivid hues. A moonbow photo appears much like a daytime rainbow.

Muir posited that moonbows could be found “any night” at Yosemite Falls, given adequate quantities of two necessary components: moonlight and spray.

It took a physicist and a team of researchers, however, to model precisely when and where Yosemite moonbows might show. They also catalogued what Muir had missed—four more necessities in creating a moonbow.

Photos and calculations

Just a trickle of water spilled over Yosemite Falls when Donald Olson, a Texas State University professor of physics and astronomy, and a team of students carted equipment there in September 2005. They had digital cameras on tripods to record the stars and their relation to the landscape. As this was before the advent of smartphones, they relied on a short-wave radio connection to track precise photo times.

Armed with that information and computer planetarium programs back at home, they were able to accurately predict for 2006 when the moon would climb above the local horizon and arrive at the proper angle for a moonbow to appear. It’s a method of addressing celestial mysteries that Olson has since employed to unearth when classical poems were written or where Impressionist painters found their inspiration.

“Our department had a long interest in atmospheric optics—halos, rainbows, and so on,” says Olson. “When I read John Muir, I wondered if I could reproduce what he saw—where would I stand and where would the moon have to be?”

To Muir’s moonbow elixir of bright moonlight and plenty of spray, Olson’s team added four more ingredients: Clear sky around the moon, dark skies with the sun well below the horizon, moonlight unfettered by cliffs or mountains, and correct rainbow geometry.

Texas State continued predicting moonbows until about 2018. Olson retired from teaching and moonbow prediction in 2019. He and Hawkins had connected in the meantime, and Hawkins continued making the predictions for various Yosemite locations on his website.

Scouting new horizons

Moonbow chasers often follow each other’s footsteps, sharing information and inspiration.

Hawkins saw his first Yosemite moonbow in 2011—the same year he crossed paths with filmmaker Steven Bumgardner, the longtime National Park Service storyteller through his Yosemite Nature Notes series. Bumgardner created an iconic moonbow video as well as a behind-the-scenes explainer.

Bumgardner used time-lapse videography to capture images at night. But more advanced equipment later allowed Hawkins to complete a moonbow video with real-time images, the first of its kind.

Similarly sparked by Bumgardner’s pioneering work, videographer and photographer Scott Oller began hunting Yosemite moonbows in 2021. He contacted Hawkins, who coached him on predicting moonbows and scouting locations.

“Seeing a moonbow is such a visceral experience,” says Oller. “You’re in the spray, gusts of wind, this surreal quality of light, enveloped in the mist. Suddenly you see it, the arc of the moonbow with your own eyes.”

Wandering around in the dark among slick boulders and over grassy slopes carries risks, however. Muir chronicled a near-death experience of being pummeled by Yosemite Falls’ spray that left him “nerve-shaken, drenched, and benumbed.”

For most of us, the downside is limited to a thorough drenching, like driving a vehicle through a car wash with the windows down. But some moonbow seekers dare to push the limits.

Risk and reward

Back in 2012, when moonbows were still new to Hawkins, he set out alone to climb the Upper Yosemite Fall trail in darkness. It’s steep and strenuous enough in the daytime, over stone steps and shifting gravel. His goal was a little-known spot called “Oh My Gosh Point,” about one and a half miles and more than 1,000 feet of elevation from the trailhead.

Once there, he discovered he wasn’t alone. He spotted bobbing headlamps, which proved to belong to Bumgardner and another photographer. In successive nights, Hawkins kept vigil from the valley floor: white dots signaled the same pair toting gear up and down the trail after dark.

In late May 2021, amateur photographer Anna Smits, who lives and works in the park, aimed for the same Upper Yosemite Fall viewpoint at night with a few friends. Once there, she secured her rope to a railing and rappelled about 15 feet down to a narrow ledge.

“I sat crouched there for over an hour waiting for a moonbow,” says Smits.

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A vision in the spray

Hawkins and Smits share a friendship forged around Yosemite, photography and moonbows. On the afternoon of my 2026 Yosemite arrival, Hawkins texted that he and Smits were out hiking—scouting a different Bridalveil moonbow shot for that night. It would involve a midnight departure, then two hours afoot—mostly off-trail scrambling.

“No path,” he wrote. “Bring boots with good traction.”

I did. But by that evening the two had determined that the potential payoff wasn’t worth it. Instead, we followed the easy paved pathway to Lower Yosemite Fall.

As we turned a corner and the fall’s roar intensified, I spotted it: a silver arc extending about halfway across the fall’s base. On my iPhone’s screen the colors—red, yellow, blue—shone through. A light spray dusted my eyeglasses. I stood, entranced, capturing photos and visiting with other moonbow seekers.

Two, Michael Rael and Sharon Crawford of California’s Bay Area, recounted standing on this same spot in spring 2025. The waterfall soaked them solid. In the full moon’s light a year ago, the bow appeared vivid, intense—much more so than this night.

We chatted, and the wind mustered, whipping the spray. Over the fall’s roar, we heard hoots and hollers. Before our eyes, the moonbow had fully extended in the windblown water, crossing from the fall’s base to the trees along Yosemite Creek.

Conversation halted; we just watched. Then joined in spontaneous applause for Yosemite’s glorious nighttime show.

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