September is the turn into the famous Vermont fall — crisp mornings, the first blaze of color in the high country, and the great hawk and monarch migrations overhead. The harvest peaks, the apples come in, and by month's end the Green Mountains begin to glow.
Week by week in September
September 3–9
- Hawk migration builds toward its peak — sharp-shinned and Cooper's hawks, ospreys, and kestrels stream south over the ridges.
- Apples arrive in force as Vermont's hillside orchards begin their long succession of varieties, with fresh cider close behind.
- The fields turn purple and gold with New England aster and the last goldenrod — vital fuel for the migrating monarchs.
September 10–16
- Broad-winged hawks stream south in great kettles of hundreds over lookouts like Putney Mountain — the peak of the hawk flight.
- Monarchs stream south on north winds, pausing to nectar and sometimes gathering in loose evening roosts in trees along the way.
- Color flushes first in the high country and the Northeast Kingdom, the sugar maples turning orange and scarlet.
September 17–23
- The autumnal equinox around the 22nd brings nights longer than days, and the harvest moon rises big and golden over the hills.
- White-throated and white-crowned sparrows arrive and the first dark-eyed juncos return from the mountains and the north.
- Plant garlic, sow cover crops on emptied beds, and harvest and cure winter squash, pumpkins, and potatoes before frost.
September 24–30
- Peak color in the high country and the Kingdom — the Green Mountains blaze with maple, birch, and beech against the dark conifers.
- Snow geese begin staging at Dead Creek WMA, the great Champlain Valley spectacle of the fall building in the fields.
- Harvest frost-sweetened kale, leeks, and roots, pick green tomatoes ahead of a hard freeze, and start putting beds to bed.
Birds This Month
September is a fantastic fall-migration month in Vermont. Hawk migration peaks — broad-winged hawks stream south in great kettles of hundreds or thousands over the ridges around mid-month, watched from lookouts like Putney Mountain and the Green Mountain ridgelines, joined by sharp-shinned and Cooper's hawks, ospreys, bald eagles, and American kestrels. Songbird migration runs strong overnight: warblers (in muted fall plumage), thrushes, sparrows, vireos, and flycatchers move through the still-leafy woods.
Waterfowl build on the Champlain Valley wetlands, and shorebirds linger on the mudflats. White-throated and white-crowned sparrows arrive, and the first dark-eyed juncos return from the mountains and north. Common loons begin staging on the larger lakes, and ruby-throated hummingbirds depart through the first half of the month.
This month's tip: a clear morning after a cold front with north winds is the time for migration — visit a ridgetop hawk watch mid-month for the broad-winged spectacle, and leave hummingbird feeders up for late stragglers and possible western vagrants.
What's Blooming
September is the last full month of wildflowers, dominated by the asters and the fading goldenrods. The fields and roadsides are purple and gold with New England aster (the showiest, in deep violet), heath, calico, and panicled asters, and the last Canada and tall goldenrod — together the final great nectar source for migrating monarchs and late bees.
Damp meadows still hold joe-pye weed going to seed, late turtlehead, great blue lobelia, and the deep blue of closed (bottle) gentian. Sunny spots carry late black-eyed Susan, evening primrose, boneset, sneezeweed, and jewelweed in the moist shade, its seedpods popping at a touch. Gardens hold on with sedum, dahlias, sunflowers, and chrysanthemums. As frost approaches in the cold valleys late in the month, the wildflower season winds toward its close, the seed heads now feeding the birds.
Garden This Month
September is harvest-and-prepare month in the Vermont garden, racing the first frost. Bring in the warm-season crops — tomatoes, peppers, eggplant, beans, cucumbers, and summer squash — as the frost date nears, and harvest and cure the storage crops: winter squash, pumpkins, potatoes, onions, and carrots. Pick green tomatoes ahead of a hard freeze to ripen indoors, and keep cold-hardy kale, chard, spinach, lettuce, and roots going for fall harvest, protected on cold nights.
This is the best month to plant garlic toward its end (and again in October), to sow cover crops like winter rye and oats on emptied beds to protect and build the soil, and to divide and plant perennials while the soil is warm and roots can establish before winter. Plant spring bulbs late in the month, clean up spent and diseased plant debris, and start the slow work of putting the garden to bed for the long Vermont winter.
Zone 3b (Northeast Kingdom & high country): frost arrives this month — harvest tomatoes and tender crops ahead of the first hard freeze, and bring in winter squash and pumpkins. Plant garlic late in the month and sow cover crops on emptied beds.
Zone 4b (central Vermont & valleys): the first frost typically comes mid-to-late September. Harvest warm-season crops before it, cure squash and onions, plant garlic, sow cover crops, and keep cold-hardy greens going under cover for fall eating.
Zone 5a (lower Champlain Valley): the warmest zone often escapes frost until late September or October. Keep harvesting, plant garlic toward month's end, sow cover crops and a final round of fast greens, and divide perennials while the soil is still warm.
What's at the Farmers Market
September markets are rich with the harvest and the turn toward fall. Apples arrive in force — Vermont's hillside orchards begin their long succession of varieties — alongside the last sweet corn, tomatoes, peppers, eggplant, beans, and the new fall crops: winter squash, pumpkins, potatoes, onions, leeks, cabbage, broccoli, cauliflower, Brussels sprouts, and crisp fall greens. Plums, late peaches, grapes, and the first fresh cider appear.
Cut flowers — sunflowers, dahlias, asters — and ornamental gourds and cornstalks signal the season, with cheese, eggs, honey, maple, and meats as ever. Choose apples that are firm and heavy and store them cold to hold their crispness for weeks. Pick winter squash and pumpkins with hard rinds and dry, corky stems and keep them cool and dry — not refrigerated — for long winter keeping. Store tomatoes at room temperature, and keep cured onions and garlic cool, dry, and airy.
Night Sky This Month
September brings the autumnal equinox around the 22nd, with the nights finally longer than the days and full darkness returning at a reasonable hour. The summer Milky Way and the Summer Triangle still ride high in the early evening, while the autumn constellations take over the east: the great square of Pegasus, the chained figure of Andromeda — and within it the Andromeda Galaxy, the most distant object visible to the naked eye, a faint smudge from Vermont's dark skies.
The harvest moon, the full moon nearest the equinox, rises big and golden over the hills. There's no major meteor shower this month, but the crisp, increasingly clear nights are excellent for the Milky Way and deep-sky targets, and the lengthening nights raise the odds of catching the aurora on the northern horizon.
For this year's harvest-moon date, planet positions, and aurora outlook, see the printable Vermont night-sky guide for your part of the state.
Butterflies & Pollinators
September is monarch-migration month in Vermont. The monarchs stream south now, riding cold fronts and pausing to nectar on goldenrod and asters, sometimes gathering in loose evening roosts in trees along their route — the most remarkable butterfly event of the Vermont year, as these individuals fly all the way to the Mexican mountains. Watch open fields, lakeshores, and ridgelines on sunny days with north winds for the steady southward drift.
Other migratory species move too — painted ladies, American ladies, red admirals, common buckeyes (a southern visitor that turns up some falls), and cloudless sulphurs in big flight years. The resident late-summer butterflies linger while the weather holds: orange and clouded sulphurs over the clover, cabbage whites, late fritillaries, crescents, and skippers, and the eastern comma and mourning cloak on fallen fruit and sap — the mourning cloaks now feeding to survive the coming winter as adults.
What to plant for them is in the Vermont native plants guide
Trees This Month
September is when the legendary Vermont fall begins. The color starts in the high country and the cold north — the Northeast Kingdom and the upper Green Mountain slopes flush first in mid-month — and works downhill and southward through the weeks. The sugar maple leads the show, turning brilliant orange, scarlet, and gold, joined by the deep red of red maple, the clear yellow of birch and aspen, the bronze of beech, and the purple of white ash.
Peak color in the high country and the Kingdom usually falls in late September, with the valleys following into early October. The tamaracks in the bogs are still green, the last to turn. Meanwhile the trees finish the harvest: acorns drop from the oaks, beechnuts from the beeches, and the maples cast their winged samaras spinning down. The conifers — balsam fir, red spruce, pines, and hemlock — hold their green, dark backdrops to the blazing hardwoods as Vermont enters its most famous season.
Weather & Daylight
Across Vermont, a typical September day averages a high near 69°F and a low near 47°F, with about 3.9 inches of precipitation — statewide averages from the 1991–2020 U.S. climate normals.
Warmth eases gently, highs around 69F and crisper 47F nights bring the first hint of fall to the air.
| Average high | 69°F |
|---|---|
| Average low | 47°F |
| Precipitation | 3.9 in |
| Sunrise (mid-month) | 6:29 ET |
| Sunset (mid-month) | 19:03 ET |
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 (ET).
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One short note when Vermont's next month turns — what's arriving, blooming, and worth a night outside.
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Same month elsewhere: September in Virginia · September in Washington · September in West Virginia