June is high summer in the lowlands and the start of the great mountain bloom, as wildflowers march up toward treeline and the montane forests fill with nesting birds. Cottonwood seed drifts along the rivers, the foothills and ponderosa parks blaze with paintbrush and lupine, and the long, warm nights open the Milky Way over Colorado's dark skies.
Week by week in June
June 4–10
- As Trail Ridge Road opens, white-tailed ptarmigan, American pipits, and brown-capped rosy-finches become reachable on the tundra.
- The montane meadows blaze with silvery lupine, scarlet paintbrush, mule's-ears, and sulphur flower.
- Western tiger and two-tailed swallowtails reach their peak in the foothill canyons and river corridors.
- Keep hail cover ready for Front Range afternoon thunderstorms that can shred crops in minutes.
June 11–17
- Grassland breeders sing in full on the plains — lark buntings, longspurs, and burrowing owls on the prairie-dog towns.
- The Rocky Mountain columbine opens in the aspen groves and shaded forest openings, building toward its July peak.
- The state insect, the Colorado hairstreak, emerges in the Gambel oak scrub, a purple gem active at dusk.
- The Summer Triangle climbs in the east and the Milky Way arches up behind it in the late hours.
June 18–24
- The solstice brings the year's latest twilight; wait for full darkness after 10 p.m. for the rising summer Milky Way.
- Subalpine meadows fill with glacier lilies and marsh marigold at the receding snowbank edges.
- Quaking aspen stand in full shimmering leaf and shed their own fluffy seed across the high slopes.
- In the mountains, the brief season opens, but keep frost cloth handy — a June freeze is possible at altitude.
June 25 – July 1
- The alpine tundra breeders are at their best along Trail Ridge Road — go at dawn, before the monsoon storms build.
- The pale, translucent Rocky Mountain parnassian floats over the rocky tundra of the high passes.
- Indian paintbrush and silvery lupine peak across the montane meadows and ponderosa parks.
- Western Slope cherries and the first new potatoes and broccoli fill the summer market stalls.
Birds This Month
June is the height of the breeding season across Colorado's full range of habitats. In the montane forests of the Front Range and high country, the dawn chorus peaks — western tanagers, Cassin's finches, pine grosbeaks, hermit and Swainson's thrushes, ruby-crowned kinglets, mountain chickadees, and broad-tailed hummingbirds fill the ponderosa, lodgepole, and spruce-fir. The aspen groves ring with warbling vireos, house wrens, and the drumming of red-naped sapsuckers.
As the high passes open, the subalpine and alpine breeders become reachable. Along Trail Ridge Road in Rocky Mountain National Park and the high passes, look for white-tailed ptarmigan (now in mottled brown summer plumage), American pipits and horned larks on the tundra, brown-capped rosy-finches at the snowfields, and white-crowned sparrows in the krummholz. The subalpine willows hold Wilson's warblers and fox sparrows.
On the eastern plains the grassland breeders are in full song — the state bird lark bunting, Cassin's, grasshopper, and lark sparrows, McCown's and chestnut-collared longspurs, mountain plovers, and burrowing owls on the Pawnee prairie-dog towns. Riparian cottonwoods hold Bullock's orioles, yellow-billed cuckoos, and blue grosbeaks.
This month's tip: drive Trail Ridge Road soon after it opens for the season to reach the alpine tundra breeders — go early to beat the crowds and afternoon thunderstorms, and scan the snowfields and rockpiles for rosy-finches and ptarmigan.
What's Blooming
June launches Colorado's legendary mountain wildflower season, climbing the slopes ahead of summer. The foothill and montane meadows and ponderosa parks of the Front Range blaze with silvery lupine, scarlet and orange paintbrush, blue flax, wallflower, sulphur flower, and sheets of mule's-ears. The state flower, the Rocky Mountain columbine, opens its lavender-and-white blossoms in the aspen groves and shaded forest openings, building toward its July peak in the subalpine.
As the snow recedes, the subalpine meadows fill with glacier lilies and spring beauties at the melting snowbank edges, marsh marigold in the wet swales, and the first chiming bells and elephant's-heads in the high wet meadows. On the plains and sandsage prairie around the Great Sand Dunes, the prairie sunflowers, scarlet globemallow, prickly poppy, and blanketflower bloom. Every week of June carries the flower line higher up the mountains, with the grand alpine tundra show just opening at the top.
Garden This Month
June is full-throttle gardening across most of Colorado, and the defining task is managing water under the intense high-altitude sun and bone-dry air. Mulch every bed deeply, run drip irrigation on a consistent schedule, and water in the early morning so plants are charged before the midday heat — Colorado's combination of strong sun, low humidity, and frequent wind dries soil with startling speed. Finish setting out any remaining warm-season crops along the Front Range, and keep succession-sowing beans, lettuce, and greens for a steady supply.
Two Colorado hazards demand vigilance now: hail and altitude frost. Front Range afternoon thunderstorms can drop crop-shredding hail with little warning, so keep row cover or old sheets ready to throw over beds when storms threaten. In the mountains, where the short season is just opening, keep frost cloth on hand all summer, because a freeze is possible in any month above 8,000 feet. Side-dress heavy feeders, stake tomatoes and tall flowers against the wind, and start watching for the season's first squash bugs, grasshoppers, and aphids.
Zone 4b (mountain towns and high foothills): the brief mountain growing season finally opens once the early-June frost danger passes. Set out cold-hardy transplants and the toughest warm-season starts under protection, direct-sow greens, peas, and fast brassicas, and keep frost cloth handy all summer — a freeze is possible in any month at altitude. Focus on short-season, cold-tolerant varieties.
Zone 5b (Front Range cities — Denver, Boulder, Fort Collins, Colorado Springs): the garden hits full stride. Finish setting out warm-season crops, mulch deeply, and run drip irrigation consistently as the heat and dry air build. Watch for hail from afternoon thunderstorms and have row cover ready to throw over beds. Succession-sow beans and greens and side-dress heavy feeders.
Zone 6a (warmest Front Range and lower Western Slope — Grand Junction area): the heat is on. Keep everything deeply watered and heavily mulched against the intense Grand Valley sun, harvest the early summer crops, and provide afternoon shade for cool-season holdovers. Stay ahead of the first squash bugs and grasshoppers as the dry summer settles in.
What's at the Farmers Market
June is when Colorado's farmers markets hit full summer stride, with markets open across the Front Range, the Western Slope, and the mountain towns. The early-summer abundance pours in — asparagus finishing, the first strawberries, cherries from the Western Slope orchards, sweet sugar snap and shelling peas, new potatoes, spring onions, garlic scapes, and summer squash beginning.
The greens are at their best — head and leaf lettuces, spinach, chard, kale, arugula, and bunches of fresh herbs — alongside radishes, beets, turnips, and the first broccoli. Colorado pantry staples continue: local honey, eggs, grass-fed beef, bison, and lamb, and milled flour. Cut-flower bouquets, including the first sunflowers, brighten the stalls.
For selection and storage: choose firm cherries with green stems and refrigerate them unwashed; keep strawberries cold and use them quickly; store new potatoes in a cool, dark, airy spot rather than the refrigerator; and stand asparagus upright in water in the fridge to keep it crisp.
Night Sky This Month
June's nights are short but warm and inviting under Colorado's celebrated dark skies, and the summer Milky Way begins to dominate the late-evening view. The certified dark-sky sites are at their most comfortable now — Great Sand Dunes National Park beneath the 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, many of which host summer star parties.
The summer sky is rising. The Summer Triangle of Vega, Deneb, and Altair climbs in the east, the Milky Way arches up behind it in the late hours, and the heart of the galaxy in Scorpius and Sagittarius, with its glittering star clouds and the bright red star Antares, clears the southern horizon. The Big Dipper and orange Arcturus still ride high. There is no major meteor shower in June, making it a fine month to explore the globular clusters and nebulae of the summer Milky Way with a telescope.
Because planet positions change each year, check the printable Colorado night-sky guide for this year's specific viewing nights and planet visibility from your latitude. The solstice brings the year's latest twilight, so wait for full darkness after about 10 p.m. on a clear, calm night.
Butterflies & Pollinators
June is one of Colorado's richest butterfly months, with the season spread across every elevation. In the foothill canyons and river corridors, the big swallowtails are at their peak — western tiger and the great two-tailed swallowtail sail the cottonwood and willow draws — and the white-and-black Weidemeyer's admiral patrols the aspens. The state insect, the Colorado hairstreak, emerges in the Gambel oak scrub late in the month, a purple-and-black gem most active at dusk.
The montane and subalpine meadows fill with fritillaries, blues, and checkerspots as the wildflowers climb — Mormon and callippe fritillaries, the silvery blue, and a host of skippers on the lupine and paintbrush. As the high passes open, the alpine specialists finally take wing: the pale, translucent Rocky Mountain parnassian floats over the rocky tundra of Rocky Mountain National Park, joined by alpine arctics and high-country fritillaries in the brief tundra summer. On the plains, monarchs breed on the showy milkweed along the river corridors, and painted ladies and sulphurs work the prairie flowers. This is the month to walk a mountain meadow at midday and see Colorado's butterfly diversity at its fullest.
What to plant for them is in the Colorado native plants guide
Trees This Month
June is full leaf and active growth across all of Colorado's tree zones. Down on the plains and along the Front Range rivers, the great plains cottonwoods release their famous summer 'snow' — drifts of cottony seed float along every waterway and pile against the curbs and fences of the river towns. The foothill Gambel oak scrub is in full leaf, and the Western Slope orchards carry their swelling green peaches, cherries, and apples.
In the high country, the quaking aspen are in full shimmering leaf and shedding their own fluffy seed, the ponderosa pines finish their new growth and pollen shed, and the Colorado blue spruce, Engelmann spruce, subalpine fir, and lodgepole pine push fresh growth at last as the high-elevation summer finally arrives. The Rocky Mountain junipers and limber and bristlecone pines of the high, dry slopes grow slowly through the short warm season. The whole vertical sweep of Colorado's forests, from cottonwood bottoms to timberline, is now green and growing at once.
The Colorado native plants guide covers what grows with them
Weather & Daylight
Across Colorado, a typical June day averages a high near 78°F and a low near 48°F, with about 1.4 inches of precipitation — statewide averages from the 1991–2020 U.S. climate normals.
Full summer warmth arrives, highs around 78F and soft nights near 48F, with rain easing off from spring's peak.
| Average high | 78°F |
|---|---|
| Average low | 48°F |
| Precipitation | 1.4 in |
| Sunrise (mid-month) | 5:34 MT |
| Sunset (mid-month) | 20:29 MT |
Figures are statewide averages over the 1991–2020 U.S. climate normals; local conditions vary with elevation and distance from the coast. Sunrise and sunset are computed for a midstate point on the 15th (MT).
Next month's version of this page, by email
One short note when Colorado's next month turns — what's arriving, blooming, and worth a night outside.
Go deeper with the Colorado guides
The complete Colorado birding, native-plant, and night-sky references — or the whole year, week by week, in one book.
Same month elsewhere: June in Connecticut · June in Delaware · June in Washington, D.C.