This article was first published in Summit Daily News.
The 2023 leaf-peeping season has officially kicked-off in Colorado’s High Country, bringing pockets of fall color to mountainsides across the state.
Thanks to above-average precipitation in past months, forest experts say this year’s ephemeral event is likely to be one of the best in years.
“This year, aspens are just proliferating with all the successful moisture we had over the winter,” said Dan West, entomologist for the Colorado State Forest Service. “I expect the color to be more than we’ve seen in the last few years.”
West, who recently completed an aerial observation of the state’s 24 million acres of forest, said aspen trees haven’t looked this good since 2018, which he called the last great snow year prior to 2023.
The heavy snowfall of winter and spring helped make Colorado drought-free for the first time in four years this July. Though the reprieve didn’t last, it was enough to keep trees from becoming parched. Coupled with a cooler start to summer, the conditions created the perfect environment for thriving forests.
A 30-day forecast from the National Oceanic and Atmospheric Administration shows equal chances of slightly above- or below-normal temperatures in Colorado, with slightly above-normal precipitation.
Assuming there won’t be a major cold spell within that time, West said it will allow sunlight to “burn off the green colors and reveal yellows and oranges that are already present in the leaves and allow those to show through.”
As chlorophyll production declines ahead of winter, leaf pigmentation will eventually turn to red, purple and burnt orange before browning. The darker colors are the result of trapped sugar in the leaves, which eventually fall as the tree creates a protective seal between leaves and branches in preparation for dormancy, West explained.
From beginning to end, “It’s really only a 10 day to 20 day event,” West added.
Typically, color changes begin in more northern regions and where elevation is higher. But that may be slightly delayed this year because of the additional moisture still in the ground.
In Routt County, for example, “Things are still looking fairly green, even the hay in some places is holding up,” said Carolina Manriquez, lead forester for the state forest service’s Steamboat Springs office.
“Peak would probably be in the next week or two, where in previous years we were kind of there now,” Manriquez said.
While the wet weather has been a boon for forest health, it may have also led to an increase in certain tree-infecting fungi. Marssonina, a fungus that mostly targets aspens, has become more prevalent in Routt County, Manriquez. Thriving in more moist environments, the fungus can cause “Marssonina Blotch” that browns leaves.
Still, Manriquez said this shouldn’t be a problem for the vast majority of trees.
“There might be some patches that won’t show those colors, but, in general, we’re hoping for a really pretty show,” she said.
While north to south can provide a sturdy roadmap for how to follow the spectrum of color as leaves change, Colorado’s varied geography makes that less straightforward.
For example, valley areas of Routt such as Steamboat will experience peak color later than the county’s more northern parts, which are easily 2,000 feet higher than the city, Manriquez said.
West said he expects color in northern mountain areas to begin peaking by the last week of September. The central mountain region could peak by the first week of October, followed by southern areas in the second or third week.
While West said it’s hard to pick a favorite leaf-peeping spot, drives through Kebler Pass, the Dallas Divide, Rabbits Ears Pass and the Eagle River Valley never disappoint. And while aspens tend to take the spotlight, West said it’s worth keeping an eye out for riparian vegetation such as willows and cottonwoods as well as oaks, the latter of which can provide deep red and purple hues.
“Throughout our state, there are so many spots that are spectacular,” he said.
