Park City is well known for its colorful fall foliage. The trees around town put on a show of brilliant red, orange, and yellow hues that light up the hillsides and wrap the trails in tunnels of vibrant color. One of the best things to do in Park City in the fall is leaf peep, and in the past we’ve given plenty of beta on where to find the best fall leaves on your bike or your own two feet. But have you ever stopped at a grove of bright yellow Aspens and wondered how and why they change color in the fall?  

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. We all know that the Earth orbits the sun once per year. But it also wobbles . . . err tilts . . . as well. Whenever the northern hemisphere of the planet is tilted toward the sun (think late-spring and summer) then 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 light.  

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 available sunlight available to the leaves and triggering a process to wind down production of Chlorophyll.  

Behind all that Chlorophyll are Carotenoids and Anthocyanin (among others depending on the plant), pigments that are also created in the leaf. As Chlorophyll production slows, 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 

That’s the science of changing leaves. But now where and when do you find them? By about the third week in September, the lower elevation trails are peaking in color. In the first week of October, the higher elevation areas, which feature more Aspen trees, are showing their fall brilliance. But by the second 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!

We’d recommend starting 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.

Sources 

Let’s get serious—we know Park City but we’re not scientists, and we don’t use ChatGPT. Below are the sources we used to write this blog. And you can reference them as well to learn more about the science of changing leaves!  

National Weather Service 

National Geographic 

National Forest Service 

Park City Gardens Tree and Plant Reference Guide

Mid Mountain is one of the best spots to catch fall Aspen leaves in all their glory!

More Great Park City Stories & Adventures 

The Best Fall Mountain Biking in Park City

The Best Fall Hiking in Park City