Yosemite’s stunning moonbow phenomenon, also known as “night rainbows” or “lunar rainbows,” is approaching its peak season this spring. The rare event can only occur if the conditions are perfect – meaning a clear evening, a full moon, abundant water in the falls, sufficient darkness, and the perfect angle to the observer… plus a bunch of other things. John Muir once described moonbows as a “grand arc of color, glowing in mild, shapely beauty,” comparing it to a religious experience.
Yosemite’s moonbows have been captured at plenty of waterfalls around the park, and you can see a full list with helpful directions on their website.
Note that Yosemite’s conditions are still very snowy and some parts of the park are still closed following significant snowfall at the beginning of March. Check their current conditions page before you head out.
The visibility of moonbows to the human eye is limited, which is why nature photographers flock to Yosemite to capture them on camera. One such photographer, Brian Hawkins, is dedicated to predicting the ideal conditions for moonbow viewing. His experience as a mechanical engineer means he can create highly accurate 3D simulations, which help him to predict the phenomenon each year at Yosemite’s Lower Falls, Upper Falls, and Glacier Point.
For 2023, Hawkins anticipates optimal moonbow conditions from April 4-8, May 3-7, June 1-5, and June 30-July 4. It’s too early to have all the details just yet, but you can keep an eye on his predictions at the Yosemite Moonbow website, which he’ll update as the dates draw nearer.
The sun is 400,000 times brighter than the moon, so the dim arc created by a moonbow is fairly colorless to the human eye. But Hawkins explains that after giving your eyes a period to adjust (and avoiding looking at your phone or turning on a flashlight) you can begin to pick up on the spectrum of colors. That said, it will still never be quite as vivid as it appears on camera.
Be sure to learn more about moonbows, 2023 predictions, camera settings, and much more at Hawkins’ Yosemite Moonbow website. You can also check out Yosemite’s Moonbow Viewing Guide for additional information.