Colorado Nature Guide: December 2026
December is the deep, bright Colorado winter, when bald eagles fish the open rivers, the rosy-finches swarm the snowy foothill feeders, and the ptarmigan vanish white into the alpine tundra. The plains stand bleached under brilliant sun, the high country lies deep in snow, and the long, cold, transparent nights bring the year's grandest winter sky and the Geminid meteors.
What to look for this week
- Bald eagles fish the open tailwater below the South Platte and Arkansas reservoir dams as the lakes freeze.
- The Quadrantid meteor shower peaks around January 3 in a short, sharp burst best seen after midnight from a dark San Luis Valley sky.
- Deep-soak Front Range trees and evergreens on any warm, unfrozen day — winter desiccation, not cold, kills the most plants here.
- The bare plains cottonwoods along the rivers reveal the bulky stick nests of red-tailed hawks and eagles.
Birds This Month
December is prime winter birding in Colorado, and the season's signature spectacle is the gathering of the three rosy-finch species at the foothill and mountain-town feeders. The Colorado-area brown-capped rosy-finch, the gray-crowned, and the black rosy-finch all descend from the high country to swarm feeders around Estes Park and Allenspark — a winter pilgrimage for birders chasing the 'rosy-finch trifecta.' Above treeline, the white-tailed ptarmigan are pure white and all but invisible in the snow.
The plains and rivers belong to the wintering raptors and waterfowl. Bald eagles concentrate along the open South Platte and Arkansas and below the reservoir dams, fishing the unfrozen tailwater, while the eastern plains and Pawnee National Grassland hold rough-legged and ferruginous hawks, golden eagles, and prairie falcons, with flocks of horned larks and Lapland and McCown's longspurs blowing across the roads. Ducks and geese pack the open reservoirs.
December is also Christmas Bird Count season — counts across the Front Range, plains, and mountain towns draw birders out into the cold to tally the winter birds, a great way to find feeder flocks of juncos, tree sparrows, cedar waxwings, and the foothill mountain chickadees, Steller's jays, and Townsend's solitaires.
This month's tip: join a local Christmas Bird Count or visit the famous rosy-finch feeders on a cold, snowy morning — the deeper the high-country snow, the more reliably the rosy-finches drop to the foothill feeders.
What's Blooming
There are no wildflowers blooming in Colorado in December, but the winter landscape holds its own quiet character. On the eastern high plains, the cured native grasses are the show — blue grama, buffalograss, and little bluestem stand in shades of fawn, copper, and wine-red, catching the low winter sun, while the silver of fringed sage and the russet of spent rabbitbrush break the bleached grassland.
Look down into the grass and next year's flowers are already waiting. The flat green-and-gray basal rosettes of penstemons, evening primrose, and prairie sunflower hug the frozen ground, and the dark dried seedheads of sunflower, gayfeather, and yucca still stand, feeding juncos, finches, and wintering rosy-finches. The green bayonets of soapweed yucca hold their color across the plains, the most living green on a December grassland, and the foothill Gambel oak rattles its bronze marcescent leaves in the wind. This is the Colorado prairie at rest, but very much alive beneath the snow.
Garden This Month
December is the dormant heart of the Colorado garden year, but the climate keeps one task alive all winter: winter watering. Colorado's bright, dry, windy winters desiccate trees, shrubs, evergreens, and new plantings, and that drying — not the cold — is what kills them, so on any warm day when the soil is not frozen, give woody plants a deep soak. This single habit does more to bring landscape plants through a Colorado winter than anything else.
The rest of the month is protecting and planning. Check that perennial crowns, garlic, and strawberries are still well mulched after the wind strips cover, refresh the light-colored wraps that prevent sunscald on young trunks, and guard young trees and shrubs from hungry deer, elk, and rabbits driven down by mountain snow. Knock heavy, wet snow gently off evergreen branches before it breaks them. On the mild days, prune dormant fruit and shade trees while the structure is bare, and settle in to plan next year's garden and order seed — leaning, as always here, on the cold-hardy, short-season, and drought-tolerant varieties the Colorado climate demands.
Zone 3b (high mountain valleys — Leadville, Gunnison, the upper San Luis Valley): the coldest, harshest gardening country in Colorado, now locked in deep winter with brutal nighttime lows. There is nothing to plant; the work is protecting woody plants and high-tunnel structures, knocking heavy snow gently off evergreen branches before it breaks them, and planning around next year's frighteningly short sixty-to-ninety-day season.
Zone 4b (mountain towns and high foothills): deep dormancy. Make sure perennial crowns, garlic, and strawberries are well mulched against the freeze-thaw heaving, protect young trunks from sunscald and from elk, deer, and rabbits, and give woody plants a deep soak during any extended dry, unfrozen spell. Use the long winter to plan a season built on short-season, cold-hardy varieties.
Zone 5b (Front Range cities — Denver, Boulder, Fort Collins, Colorado Springs): the dormant heart of winter, but not idle. Keep up winter watering — deep-soak trees, shrubs, and evergreens on any warm day with unfrozen soil, since dry desiccation is the leading winter killer here. Prune dormant fruit trees and shade trees on the mild days, knock heavy snow off evergreens, and start planning and ordering seed.
What's at the Farmers Market
Colorado markets are at their leanest in December, but the Front Range winter and indoor markets — in Denver, Boulder, Longmont, and Fort Collins — keep a steady core of storage and protected crops through the holidays. The tables run on the harvest's keepers: San Luis Valley potatoes, storage onions, carrots, beets, parsnips, winter squash, and the new crop of dried pinto beans.
High tunnels and greenhouses carry the fresh side — cold-hardy spinach at its cold-sweetened best, kale, arugula, and microgreens. Colorado pantry staples anchor the holiday markets: local honey, eggs, grass-fed beef, bison, and lamb from the ranching country, milled flour, and the roasted and frozen Pueblo green chiles many growers still carry from the fall. Holiday wreaths and greens of blue spruce, pine, and juniper often appear at the stalls.
For selection and storage: keep potatoes and onions cool, dark, and airy, never refrigerated; trim root-crop tops before refrigerating; store winter squash in a cool, dry room; and keep dried beans and flour airtight and cool. Store tunnel greens dry and loosely bagged and use them within a few days.
Night Sky This Month
December's long, cold, exceptionally transparent nights make it one of the best stargazing months of the Colorado year, and the early darkness means a full sky of stars by dinnertime. The certified dark-sky destinations deliver under bone-dry winter air — Great Sand Dunes National Park beneath the snow-capped Sangre de Cristos, the dark-sky town of Westcliffe-Silver Cliff and its Smokey Jack Observatory, Black Canyon of the Gunnison, Dinosaur National Monument, and Jackson Lake State Park on the plains. Dress for serious mountain cold and let your eyes adapt in the dark.
The grand winter sky returns to the evening. Brilliant Orion climbs in the southeast with the Orion Nebula glowing in his sword, flanked by Taurus, the Pleiades, Gemini, Auriga, and the Dog Stars Sirius and Procyon, with the winter Milky Way arching overhead from a dark site. The year's finest meteor shower, the Geminids, peaks around December 14 — a rich, reliable shower of slow, bright meteors radiating from Gemini, often a hundred or more an hour from a dark Colorado sky.
Because moonlight and planet positions change each year and affect the Geminid view, check the printable Colorado night-sky guide for this year's specific viewing nights and planet visibility from your latitude. Pick a clear, calm night behind a cold front for the steadiest, darkest winter skies.
Butterflies & Pollinators
December is the deepest pause in the Colorado butterfly year, but a few hardy species are present, simply hidden through the cold. The state's signature overwintering adult is the mourning cloak, Colorado's most cold-tolerant butterfly, which passes the winter tucked under loose cottonwood and aspen bark, in woodpiles, and in foothill rock crevices and outbuildings; the Milbert's and California tortoiseshells shelter the same way. On a freak warm, sunny December afternoon along the Front Range, a mourning cloak can briefly emerge to bask before retreating.
Most of Colorado's butterflies wait out the winter in other forms, scaled to elevation. The state insect, the Colorado hairstreak, sleeps as an egg against the dormant buds of foothill Gambel oak, timed to hatch when the oak leafs out next summer. The alpine and subalpine species — the Rocky Mountain parnassian, the tundra fritillaries, and the high arctics — overwinter frozen as eggs and tiny caterpillars beneath the deep, insulating tundra snowpack, and the swallowtails and admirals of the riparian canyons hang as chrysalides on dead stems and bark. Leaving leaf litter, dead stems, standing native plants, and brush piles intact through winter shelters all of them until spring.
Trees This Month
The Colorado tree year is at full rest in December, and the contrast between zones is at its starkest. The high country is the realm of snow and the dark evergreens — the state tree, the Colorado blue spruce, holds its silver-blue needles along the montane streams, and the ponderosa pine, Engelmann spruce, subalpine fir, lodgepole pine, and the ancient gnarled bristlecone pines stand green and snow-laden, the bare white quaking aspen striping the slopes between them.
Down on the plains and along the Front Range waterways, the great plains cottonwoods spread bare and pale against the winter sky, their massive limbs holding the conspicuous stick nests of red-tailed hawks, great horned owls, and bald eagles. The foothill Gambel oak scrub rattles its bronze marcescent leaves in the wind, and the Rocky Mountain junipers stay deep green and heavy with frosted blue berry-cones, sheltering and feeding wintering Townsend's solitaires, robins, and waxwings. The planted blue spruce and juniper of the towns also supply the boughs and wreaths of the Colorado holiday season.
Go deeper with the Colorado guides
The complete Colorado birding, native-plant, wildflower, and night-sky guides — or the whole year in one bundle.
Same month elsewhere: December in Connecticut · December in Delaware · December in Washington, D.C.