Record-breaking drought in the Mountain West has contributed to wildfire conditions, low reservoirs, and has hurt agriculture and recreation. But as temperatures cool down after a hot summer, that drought could also affect how fall colors bloom on trees across the region.
Dan West, the state forest entomologist with the Colorado State Forest Service, said every time a tree photosynthesizes, it uses water. This year's drought means that trees have had less of that scarce resource.
“When we're in these extreme droughts and really warm temperatures like we've been seeing, trees then start to shut down those processes or can shut down those processes slightly earlier,” he said. “When they do that, we can start to see things accelerate a little bit.”
“As a response, trees just say, ‘Well, if I shed my leaves slightly earlier, I can stop all this water loss and then I can just prepare for next year,’” he said. “That's kind of what's happening across most of the state.”
That means that fall colors in Colorado and the rest of the Rocky Mountain West could peak a few weeks earlier than usual.
West said fall colors are already baked into leaves well before they turn, starting in March and April when trees are slowly absorbing water from snowpack in their roots. Because water has been scarce for a long time, those colors likely haven’t developed like they usually do.
“The colors that we see— they become more vibrant if they have an adequate amount of water, and they become more dull as they start to lose that water or as water resources become limited,” West said.
Drought-stressed trees will begin to brown around the edges of leaves, and there may be some yellowing around the veins of those leaves—and while they may look colorful from far away, the effect is not as attractive up close. Trees that produce the vibrant colors beloved by leaf peepers are also struggling more generally, West said.
“Looking at some of our aspen trees and some of our cottonwoods and some of the trees that are along our riverways, many of the trees just showed very poor growth going into this summer,” he said. “That translates to they just don't have as full of a crown, or they don't have as many leaves in the crown of the tree.”
According to West, a healthy aspen tree should see about five inches of growth in its branches each year. Across Colorado, he estimated that growth this year was closer to one or two inches.
This year’s drought will have ripple effects, too. West says we’ll likely need a couple years of average to above-average precipitation to get Colorado’s trees back to a healthy place.
“From a tree perspective and a forest health perspective, we really need two years of average precipitation strung together back to back,” he said. “Trees can't capture all the water that they need from just one year, and so we really need a prolonged winter where we get average or above-average precipitation.”
This spring was also problematic for tree health. March brought a heat dome that shattered records and caused an extremely fast melt-off for what little snowpack remained after a dismal winter—adding stress to the drought-parched trees.
“What's most helpful is that we have a really slow warmup,” West explained. “Those springs where it just all of a sudden goes from being cold to really warm, that means a whole lot of snow is coming off super quick. It's not percolating down through the soil column where trees can capture as much as they need, and we want it to melt slowly so that trees can continuously capture it.”
West says the problems we’re seeing with Colorado’s forests right now are directly connected to human-caused climate change, which brings far greater variability year to year, and wild deviations from historic averages for precipitation and temperature.
“As we get warmer and warmer and our precipitation regime oscillates every year, it just makes it harder and harder to be a tree in Colorado,” West said.
Copyright 2026 Rocky Mountain Community Radio. This story was shared via Rocky Mountain Community Radio, a network of public media stations in Colorado, Wyoming, Utah, and New Mexico, including Aspen Public Radio.
