Why Do Leaves Change Color in the Fall

Park City is well known for its colorful fall foliage. The deciduous forests around town put on an annual show of brilliant red, orange, and yellow hues—dancing in the light and wrapping the hills in a mosaic of vibrant color. One of the best things to do in Park City in the fall is leaf peep, either under the crown of towering aspen forests or from an alpine view point. We’ve given plenty of beta on where to find the best fall leaves on your bike or your own two feet, but their is another side to these incredible colors that we feel is worth knowing about—how exactly and why these incredible color changes happen.

Fall is all about focusing on the colorful yellows and golds!

Hiding Their True Colors

It turns out that leaves on trees such as Quaking Aspen, Scrub Oak, and Choke Cherry (just a few natives to Park City) are hiding their true colors throughout spring and summer. As the Earth orbits the sun once per year it also wobbles . . . err tilts . . . as well. Whenever the northern hemisphere of the planet is tilted toward the sun (think late-spring and summer) the days are longer and warmer.

As the seasons turn, the trails are surrounded by intense shows of color!

These longer summer days boost Chlorophyll production, a compound used in photosynthesis to produce sugar molecules for the tree or plant to consume. Leaves appear green as the heightened Chlorophyll reflects the green wavelength of visible light.

Fall in Park City | 7 min read

Hikes to Peep Park City’s Fall Foliage

Fall in Park City is nothing short of spectacular. The hills are painted with incredible hues of red, orange, yellow as the leaves lose their summer greens and transition to fall. Mornings and nights are cool with winter whispers of chilled air, calling for cozy sweaters and light jackets…

Yellow and other pigments are revealed as the days grow shorter and there is less sunlight for photosynthesis!

Come fall, the northern hemisphere tilts aways from the sun, resulting in less sunlight available to the leaves and signaling the coming change of seasons. This triggers a process to wind down Chlorophyll production.

Behind all that Chlorophyll are Carotenoids and Anthocyanin (among others depending on the plant), pigments created in the leaf. As Chlorophyll production there is less to show, and these pigments start to show off their radiant reds, oranges, and yellows. Depending on the tree, you will get different levels and combinations of these pigments. That’s why a Scrub Oak on the Lost Prospector trail or in Round Valley will produce a brilliant red. And Aspen leaves along Mid Mountain turn yellow.

At the end of this process, the tree or plant builds a wall of cells that close off the veins of the leaf, leaving it to shrivel and fall to the ground.

How do Weather Conditions Affect Fall Leaf Colors

Park City is located in a high-altitude desert, at about 7,000’ elevation. Our seasons are fairly consistent, but it is not out of the ordinary to receive sudden warm or cold snaps, heavy precipitation, and other weather patterns that are conducive to living in the mountains.

Fall leaves create a kaleidoscope of colors when mixed with other natural features!

For the most brilliant fall colors, warm days and cool nights ensure the leaf continues to produce sugars via photosynthesis while slowly winding down Chlorophyll production. A cold snap or heavy rainfall can disrupt this process, leading the leaves to prematurely shrivel and fall.

When & Where to Find the Best Fall Leaves in Park City

So, how do you know when and where to find the best fall leaves? By about the third week in September, the lower elevation trails in Park City are peaking in color. This includes Round Valley, Lost Prospector, and Treasure Hill. In the first week of October, the higher elevation areas, which feature more Aspen groves, are showing their fall brilliance. But by the second or third week in October, the ground is blanketed by crunchy fall leaves.

Good view points and lots of Aspen trees make for epic fall scenery in Park City!

For the best fall leaves in Park City, start somewhere that combines good views and forest cover with a variety of trees and plants for maximum fall color effect.

Trails like Armstrong weave through canopies of Aspen and Gambel Oak and are both hike and bike friendly. Free Mason and Lost Prospector are great too as the foliage makes for an incredible tunnel effect and wraps you in fall colors.

As the season continues to turn into October, head higher to Mid Mountain and Bonanza Flats to see Aspen groves turn fiery hues of yellow and orange. The larger groves are a truly magnificent site to see as they overflow with incredible colors and they are set against an amazing high alpine backdrop.

Sources

Let’s get serious—we know Park City but we’re not scientists. Below are the sources we used to write this blog. You can reference and share them to learn more about the science of changing leaves!

National Weather Service

National Geographic

National Forest Service