Yosemite’s moonbows are uncommon, nocturnal phenomena. Here’s tips on how to see one.

As midnight nears, the roads circling Yosemite Valley seem all however deserted. Car headlights freeze a mule deer crossing the roadway. A coyote limps by, nursing a foreleg. To the south, darkish, hulking outlines trace on the sheer partitions encasing the valley of California’s most iconic nationwide park. But to the north, from El Capitan to past Yosemite Falls, grey granite faces are awash in heat moonlight. The glow beckons us.

A knot of onlookers has gathered on the falls’ roaring base, telephones and cameras on the prepared. They are searchers, drawn by the total moon’s promise of unveiling moonbows, a uncommon, nocturnal model of rainbows. Yosemite National Park brims with wonders in any season, and for just a few months every year, moonbows rise with them.

Yosemite stays one among Earth’s few locations the place nature persistently conjures moonbows. The park is blessed with plentiful waterfalls, together with one among North America’s tallest. Peak moonbow season follows the lunar cycle from spring to mid-summer, however a comparatively dry winter and early snowmelt imply the final predictable alternative for 2026 might be May 28 by June 3.

I do know this as a result of I’m a moonbow hunter. Like me, many others following headlamps towards the sound of falling water this April are neophytes. Through a shared curiosity and experience, we depend on others to foretell this dazzling dance between lunar gentle and water.

For the second time within the final three years, Brian Hawkins has agreed to traipse across the park with me. He didn’t originate the apply, however since 2018 he has posted Yosemite moonbow predictions on-line.

Overcast skies plagued the final journey, however tonight the moon shines brightly, stalking our steps on the method to Lower Yosemite Fall. As the waterfall’s roar intensifies, Hawkins flicks me a query: “Are you ready to see a moonbow?”

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Muir’s lunar rainbows

Naturalist John Muir, who launched Yosemite to the world within the nineteenth century, characterised the total moon’s impact on waterfalls as lunar rainbows, or spray-bows.

Much just like the aurora borealis, moonbows to the bare eye often seem shrouded in shades of grey and white. That’s due to how our eyes’ sensors perform: activated in low gentle, photoreceptors referred to as rods fail to instantaneously distinguish colours. Modern digital cameras, nevertheless, collect sufficient gentle by longer exposures to document vivid hues. A moonbow picture seems very like a daytime rainbow.

Muir posited that moonbows might be discovered “any night” at Yosemite Falls, given satisfactory portions of two needed parts: moonlight and spray.

It took a physicist and a group of researchers, nevertheless, to mannequin exactly when and the place Yosemite moonbows may present. They additionally catalogued what Muir had missed—4 extra requirements in making 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 group of scholars carted gear there in September 2005. They had digital cameras on tripods to document the celebrities and their relation to the panorama. As this was earlier than the arrival of smartphones, they relied on a short-wave radio connection to trace exact picture occasions.

Armed with that info and pc planetarium packages again at dwelling, they have been capable of precisely predict for 2006 when the moon would climb above the native horizon and arrive on the correct angle for a moonbow to seem. It’s a technique of addressing celestial mysteries that Olson has since employed to unearth when classical poems have been written or the place Impressionist painters discovered 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 vivid moonlight and loads of spray, Olson’s group added 4 extra components: Clear sky across the moon, darkish skies with the solar properly beneath the horizon, moonlight unfettered by cliffs or mountains, and proper rainbow geometry.

Texas State continued predicting moonbows till about 2018. Olson retired from instructing and moonbow prediction in 2019. He and Hawkins had linked within the meantime, and Hawkins continued making the predictions for numerous Yosemite areas on his web site.

Scouting new horizons

Moonbow chasers typically comply with one another’s footsteps, sharing info and inspiration.

Hawkins noticed his first Yosemite moonbow in 2011—the identical yr he crossed paths with filmmaker Steven Bumgardner, the longtime National Park Service storyteller by his Yosemite Nature Notes collection. Bumgardner created an iconic moonbow video in addition to a behind-the-scenes explainer.

Bumgardner used time-lapse videography to seize photos at evening. But extra superior gear later allowed Hawkins to finish a moonbow video with real-time images, the primary of its type.

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

“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 round at midnight amongst slick boulders and over grassy slopes carries dangers, nevertheless. Muir chronicled a near-death expertise of being pummeled by Yosemite Falls’ spray that left him “nerve-shaken, drenched, and benumbed.”

For most of us, the draw back is restricted to an intensive drenching, like driving a car by a automobile wash with the home windows down. But some moonbow seekers dare to push the bounds.

Risk and reward

Back in 2012, when moonbows have been nonetheless new to Hawkins, he set out alone to climb the Upper Yosemite Fall path in darkness. It’s steep and strenuous sufficient within the daytime, over stone steps and shifting gravel. His purpose was a little-known spot referred to as “Oh My Gosh Point,” about one and a half miles and greater than 1,000 toes of elevation from the trailhead.

Once there, he found he wasn’t alone. He noticed bobbing headlamps, which proved to belong to Bumgardner and one other photographer. In successive nights, Hawkins stored vigil from the valley flooring: white dots signaled the identical pair toting gear up and down the path after darkish.

In late May 2021, beginner photographer Anna Smits, who lives and works within the park, aimed for a similar Upper Yosemite Fall viewpoint at evening with just a few buddies. Once there, she secured her rope to a railing and rappelled about 15 toes all the way down to a slender ledge.

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

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A imaginative and prescient within the spray

Hawkins and Smits share a friendship solid round Yosemite, images and moonbows. On the afternoon of my 2026 Yosemite arrival, Hawkins texted that he and Smits have been out climbing—scouting a distinct Bridalveil moonbow shot for that evening. It would contain a midnight departure, then two hours afoot—largely off-trail scrambling.

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

I did. But by that night the 2 had decided that the potential payoff wasn’t price it. Instead, we adopted the simple paved pathway to Lower Yosemite Fall.

As we turned a nook and the autumn’s roar intensified, I noticed it: a silver arc extending about midway throughout the autumn’s base. On my iPhone’s display screen the colours—purple, yellow, blue—shone by. A light-weight spray dusted my eyeglasses. I stood, entranced, capturing photographs and visiting with different moonbow seekers.

Two, Michael Rael and Sharon Crawford of California’s Bay Area, recounted standing on this similar spot in spring 2025. The waterfall soaked them strong. In the total moon’s gentle a yr in the past, the bow appeared vivid, intense—way more so than this evening.

We chatted, and the wind mustered, whipping the spray. Over the autumn’s roar, we heard hoots and hollers. Before our eyes, the moonbow had totally prolonged within the windblown water, crossing from the autumn’s base to the bushes alongside Yosemite Creek.

Conversation halted; we simply watched. Then joined in spontaneous applause for Yosemite’s wonderful nighttime present.

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