Ready your iPhones and picnic blankets: Colorado’s leaf peeping season is here. 

As summer wanes and fall approaches, pockets of yellow aspen trees are becoming more and more abundant. Within weeks, the High Country will be awash in fall color. 

“It looks like it’s going to be a great season,” said Dan West, who specializes in forest health for the Colorado State Forest Service.

Speaking last week during his annual aerial survey of the state’s 24 million acres of forest, West said aspen trees are looking healthy thanks to a strong snowpack and wet end to the summer. 

While snowpack lagged in early winter, levels surged above normal from mid-March through mid-April and remained near or slightly above normal through the runoff season in May and June. And despite a delayed monsoonal pattern, August defied initial expectations with elevated precipitation that, in some parts of the High Country and Western Slope, was anywhere from 200% to 300% above normal, according to meteorologists. 

“We had an above-average snowpack and, for the most part, a modestly moist summer. So I would say that the tree color would be healthy and typical for a fall in northwestern Colorado,” said Samuel Hahn, a forester for the Hahns Peak/Bears Ears Ranger District north of Steamboat. 

“Aspen requires quite a lot of water compared to other trees in the springs to develop a good leaf cover,” Hahn added. 

The big question: When and where will colors peak? 

A map released this week by SmokyMountains.com, a travel brand promoting the Smoky Mountain region, provides an estimate of how fall foliage will change across the U.S. from now through November. The group has built and released predictive maps since 2013, relying on myriad data sources including historic temperature and precipitation trends, upcoming forecasts and user data from different regions. 

The map can be viewed online at SmokyMountains.com/fall-foliage-map. 

Interactive Fall Foliage Forecast Map

“Similar to any meteorological forecast that is dependent on weather variables, the leaf predictions are not 100% accurate,” SmokyMountains.com said in a statement, adding that the group encourages users to send in their own photos and foliage reports to improve future maps.

Zooming in on Colorado, the 2024 map predicts foliage colors will last between the third week of September and the third week of October, with the northwestern parts of the state peaking earlier and southwestern areas peaking later. 

The predictions mostly line up with what state forest experts believe. 

According to West, the Colorado State Forest Service scientist, mid- to late-September is likely to be the best time for color in northern Colorado while areas along the Interstate  70 corridor, such as Eagle and Summit counties, could peak around the end of September or early October. 

Aspen and the Roaring Fork Valley can see peak color persist into the first week of October while further south, the San Juans may see concentrated foliage into the second and third week of October. 

While the pattern is fairly consistent year-over-year, West said the optimal time for when to catch fall color is dependent on short-term weather trends. 

Warm days and cool nights are the perfect combination for strong color. The more uninterrupted time an aspen tree has in the sunlight, the more the leaves will “burn off the green and amplify all those oranges and reds that come out,” West said. 

The natural process is part of how a tree readies itself for winter. As chlorophyll production slows, leaf pigmentation eventually turns to red, purple and burnt orange before browning. The brown leaves then fall from the tree as it creates a protective seal between leaves and branches to prepare for dormancy.

Aspen leaf pigmentation can be influenced by temperature and exposure to sunlight, with West adding that cooler temperatures can lead to darker colors. While it’s fine for temperatures to teeter above or below normal, the duration of leaf peeping season can be cut short by extreme temperature swings that cause leaves to drop early. 

September in Colorado is forecast to have a 60% to 70% chance of above-normal temperature and a 33% to 40% chance of below-normal precipitation, according to a forecast issued by the Climate Prediction Center.

Barring any major cold snaps, West said the weather and precipitation predictions “are about the right recipe we need to have a good aspen show.”

Some of the state’s most reliable spots to see prime fall color include drives through Kebler Pass, the Dallas Divide, Rabbits Ears Pass and the Eagle River Valley. But visitors to most anywhere in the High Country will be spoilt for choice — so long as they don’t wait too long. 

“If you’re wanting to see more gold over yellow, the goal is to fill up your gas tank and keep driving,” West said.