September turns Utah's high country gold as the aspen begin their famous turn, the raptor migration streams along the Wasatch ridges, and the harvest peaks with peaches, apples, and Bear Lake raspberries. The first frosts touch the mountain valleys while the canyon country cools into its finest hiking weather.
Week by week in September
September 3–9
- Raptor migration streams along the Wasatch ridges — Cooper's and sharp-shinned hawks, kestrels, and the first golden eagles riding the thermals.
- Rabbitbrush reaches its brilliant golden peak across the valleys and foothills, still humming with the last bees and butterflies.
- The state tree's fall turn begins in the high country as the first aspen stands gild the upper Wasatch and Uinta slopes.
September 10–16
- Aspen blaze gold across the Wasatch and Uintas, drawing leaf-watchers up the Alpine Loop and the canyon scenic byways.
- The apple harvest builds at the Wasatch Front orchards as the last peaches and Green River melons hold on.
- Sandhill cranes stage in the valleys, and sparrow migration fills the brushy edges with white-crowned and Lincoln's sparrows.
September 17–23
- Whole mountainsides blaze gold and orange at the aspen peak, one of the West's great autumn spectacles, with bigtooth maple flaming red below.
- The autumnal equinox brings the Great Square of Pegasus and the naked-eye Andromeda Galaxy high over the dark canyon country.
- Migrating butterflies and the last monarchs crowd the golden rabbitbrush as the high-country flight ends in frost.
September 24–30
- The first big flocks of returning waterfowl — pintail, teal, and shoveler — build at Bear River as the Eared Grebe staging flocks remain enormous.
- Harvest the last winter squash and pumpkins before the bench frost, plant garlic for next year, and cover tender crops on cold nights.
- Apples peak alongside winter squash and pumpkins as harvest festivals and corn mazes mark the season across the state.
Birds This Month
September is a second great Utah birding month, driven by fall migration. The raptor migration streams along the Wasatch and other ridges — count sites watch Cooper's and sharp-shinned hawks, red-tailed and Swainson's hawks, American kestrels, northern harriers, ospreys, and the first golden eagles riding the thermals south. Songbird migration peaks in the riparian canyons, with warblers, vireos, western tanagers, flycatchers, and sparrows moving through.
On the Great Salt Lake, shorebird migration continues, the Eared Grebe staging flocks remain enormous, and the first returning waterfowl — northern pintail, green-winged teal, and shovelers — build at Bear River and Farmington Bay. White-faced ibis flock and stage before departure. In the mountains, the high-elevation breeders move downslope, mountain bluebirds gather in loose flocks over the meadows, and Clark's nutcrackers cache pinyon and whitebark seed. Sandhill cranes stage in the valleys for their southbound flight.
What's Blooming
September is Utah's golden late-season bloom. The valleys and foothills glow with rabbitbrush at its brilliant peak, joined by native sunflowers, goldenrod, blanketflower, broom snakeweed, and clouds of purple and white asters — the rabbitbrush still humming with the last butterflies and bees. The high meadows fade, holding only the latest gentians, asters, and the magenta seed-fluff of fireweed.
In the canyon country, the cooling monsoon season keeps the desert benches greener than usual, with late sacred datura, desert four o'clock, and sunflowers lingering in the washes. Gardens carry the season's strongest color — sunflowers, dahlias, zinnias, chrysanthemums, asters, and black-eyed Susans — before the first frosts. As the foothill grasses cure to tawny gold and the aspen begin to turn, the rabbitbrush gold is the signature wildflower color of a Utah September.
Garden This Month
September is the great harvest-and-transition month in the Utah garden, with the first frosts looming. On the Wasatch Front, gather the last big flush of tomatoes, peppers, eggplant, melons, winter squash, and pumpkins, and watch the forecast — the first frost often comes in late September on the benches and earlier in the cold valleys. Cover tender crops on the first cold nights to stretch the harvest, and pick green tomatoes ahead of a hard freeze to ripen indoors.
This is prime time to plant garlic for next summer, sow spring-flowering bulbs, and set out cool-season spinach, lettuce, and greens under cover for fall. Harvest and cure winter squash and the last onions and potatoes in the dry air, dig carrots and beets, and start cleaning up spent beds. In St. George the warm-season garden runs on into fall and a second cool-season planting goes in; in the high Uinta Basin and mountain valleys, frost has likely already ended the tender crops and the focus turns to harvest, cleanup, and garlic. Compost the healthy debris and plan cover crops on the dry soil.
Zone 4b (Uinta Basin & mountain valleys): frost arrives early — pull or cover tender crops, harvest the last squash and roots, and plant garlic for next year before the ground hardens.
Zone 5b (Wasatch Front benches): harvest the last tomatoes, peppers, melons, and winter squash before the first frost (often late September on the benches); plant garlic and spring bulbs, and cover tender crops on cold nights.
Zone 6b (warmer valley floors): keep harvesting the warm-season glut, sow a final spinach and lettuce crop, and plant garlic mid-to-late month. Frost is near, so watch the forecast.
What's at the Farmers Market
September markets in Utah brim with the harvest's peak. Peaches continue strong on the Wasatch Front and at the Green River desert stands, joined by the building apple harvest — many varieties from the bench orchards — plus pears, plums, and grapes. Bear Lake raspberries linger from the cool high valley, and Green River melons and watermelons remain at their best.
The vegetable abundance peaks: tomatoes, peppers, winter squash, pumpkins, sweet corn, onions, potatoes, beans, and the first cool-season greens returning. New-crop honey from the summer and rabbitbrush bloom is abundant, with farm eggs, cut flowers, and grass-fed meats. The big Wasatch Front and Park City markets are at peak diversity, southern Utah roadside fruit stands sell the last peaches and melons, and harvest festivals — including Brigham City's Peach Days — celebrate the orchard bounty across the state.
Night Sky This Month
September's longer, cooler nights and the autumnal equinox bring excellent stargazing to Utah's dark parks, with the summer Milky Way still high and crowds thinning. Bryce Canyon, Capitol Reef, Canyonlands, Arches, Natural Bridges, and Cedar Breaks all offer pristine fall skies, and the high-desert rims remain among the darkest in the country. Near the Wasatch Front, Antelope Island State Park and the Stansbury Park Observatory give accessible autumn viewing as the air dries and steadies.
The sky shifts toward autumn: the Summer Triangle still rides high after dark, but the Great Square of Pegasus climbs in the east, leading the faint autumn constellations Andromeda and Pisces, with the Andromeda Galaxy well placed and visible to the naked eye under Utah's dark skies. The summer Milky Way sets earlier each night. No major meteor shower peaks this month, making it fine for galaxy and deep-sky viewing; the printable Utah night-sky guide lists this year's planet positions and the best dark-sky dates.
Butterflies & Pollinators
September keeps Utah's butterflies flying while the season winds down, with the rabbitbrush bloom as the great late-season draw. Migrating and resident butterflies crowd the golden flowers across the valleys and foothills — painted ladies, fritillaries, checkerspots, sulphurs, and especially the Mormon metalmark, whose flight peaks with the snakeweed and rabbitbrush. The last monarchs drift south toward coastal California to overwinter, fueling up on rabbitbrush and aster as they go.
In the canyons, western tiger swallowtails show a final flight, and the cooling mountain meadows hold only the latest fritillaries and sulphurs before frost. Mourning cloaks and tortoiseshells feed up to enter hibernation as adults. This is the last strong butterfly month of the year and a fine time to watch the migration on rabbitbrush; leaving the late nectar standing and the brush piles intact helps the species that overwinter here. By month's end the high country has frozen and gone still.
Trees This Month
September begins Utah's celebrated fall color in the high country. The state tree, quaking aspen, turns first and most brilliantly — by mid-to-late month whole mountainsides of the Wasatch, Uintas, and Boulder Mountain blaze gold and occasional orange, one of the West's great autumn spectacles, drawing leaf-watchers up the Alpine Loop and the canyon scenic byways. The bigtooth maple on the foothills flames red and orange among the gold.
Down in the valleys, the Fremont cottonwoods along the rivers begin to yellow, and the Gambel oak turns bronze and russet on the benches. The native chokecherry and serviceberry color along the draws. In the high spruce-fir forest, the conifers hold dark green as a foil to the golden aspen. The plateau pinyon-juniper stands steady, pinyon nuts ripening for the fall harvest by jays and nutcrackers. In the far southwest, the desert woodland cools as the long Dixie summer finally eases.
Weather & Daylight
Across Utah, a typical September day averages a high near 77°F and a low near 48°F, with about 1.2 inches of precipitation — statewide averages from the 1991–2020 U.S. climate normals.
Summer eases its grip, highs near 77F feel comfortably warm while nights near 48F bring a refreshing, sweater-worthy coolness.
| Average high | 77°F |
|---|---|
| Average low | 48°F |
| Precipitation | 1.2 in |
| Sunrise (mid-month) | 7:08 MT |
| Sunset (mid-month) | 19:37 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).
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Same month elsewhere: September in Vermont · September in Virginia · September in Washington