New Hampshire Nature Guide: September 2026
Data updated: August 2026Sources & method · Corrections
September is the great pivot of the New Hampshire year — fall color begins in the mountains and the North Country, hawks and monarchs stream south, apples and pumpkins crowd the farm stands, and the first frosts touch the high valleys. The state tips from summer toward its world-famous autumn.
Week by week in September
September 3–9
- Southbound warblers, vireos, and thrushes move through the woods as fall songbird migration builds.
- Plant garlic late this month, harvest winter squash as the rind hardens, and dig potatoes for storage.
- Apples arrive in force as the orchard harvest opens, with pumpkins and the last summer crops.
- The southbound monarch river concentrates along the coast and river valleys, pausing at the fields' goldenrod.
September 10–16
- The broad-winged hawk migration peaks — thousands kettle south over Pack Monadnock and Carter Hill hawk-watches.
- Fall color begins in the mountains and North Country, the red maples flaming scarlet in the swamps.
- The harvest moon rises full and golden near the autumnal equinox.
- Pick-your-own apple farms draw crowds, with fresh cider, pumpkins, and fall greens at the stands.
September 17–23
- The sparrow migration pours south — white-throated, white-crowned, and savannah sparrows fill weedy edges.
- The White Mountains and North Country approach peak color, drawing leaf-peepers north.
- Plant spring bulbs and garlic, divide perennials, and pick green tomatoes ahead of a hard freeze.
- The autumnal equinox brings long, comfortable nights and rising aurora chances.
September 24–30
- Common loons begin leaving the lakes for the coast, and waterfowl migration strengthens on the rivers and bay.
- Witch hazel opens its spidery yellow ribbons — the last native shrub to flower — in the woods.
- Color sweeps downhill from the peaks toward the lowlands as birches and aspens turn clear gold.
- The fall harvest fills the tables with apples, winter squash, pumpkins, cabbage, and cool-season greens.
Birds This Month
September is one of the two best birding months in New Hampshire, defined by raptor migration and the southbound songbird flood. The broad-winged hawk migration peaks mid-month, when thousands stream south in swirling "kettles" — Pack Monadnock, Carter Hill, and other hawk-watch ridges are the places to be, with sharp-shinned hawks, American kestrels, ospreys, bald eagles, merlins, and peregrines in the mix.
Southbound warblers in tricky fall plumage move through the woods, along with vireos, thrushes, and flycatchers. Sparrows pour south late in the month — white-throated, white-crowned, savannah, and others fill weedy edges. Shorebirds continue on Great Bay and the Seacoast, and the first sea ducks and migrant waterfowl return. Common loons begin to leave the lakes for the coast, and ruby-throated hummingbirds mostly depart by late September. Keep feeders up for the moving sparrows and late hummingbirds.
What's Blooming
September is the grand finale of New Hampshire's wildflower year, dominated by the asters and goldenrods that blaze across every field and roadside. The New England aster peaks in deep purple, joined by white heath and calico asters, blue smooth aster, and a dozen goldenrods gone fully golden. Joe-pye weed, boneset, turtlehead, and the last cardinal flower linger in wet meadows.
The roadsides still hold Queen Anne's lace, chicory, and knapweed, and jewelweed hangs orange in the shade, its seedpods bursting at a touch. The first witch hazel — the last native shrub to flower — opens its odd yellow ribbons in the woods. Gardens close the season with sedum, sunflowers, dahlias, zinnias, mums, and the last phlox. These late blooms are the final nectar source for the migrating monarchs and the season's last bees. As the frosts begin in the north, the wildflower year winds down from the mountains toward the coast.
Garden This Month
September is harvest and wind-down in the New Hampshire garden, racing the first frosts that arrive in the north early and the south late. Bring in the warm-season crops — tomatoes, peppers, eggplant, beans, corn, melons, and squash — and pick green tomatoes ahead of a hard freeze to ripen indoors. Winter squash and pumpkins are ready when the rind hardens; cure them in the sun. Dig potatoes and cure onions and garlic for storage.
The cool-season crops now thrive: keep harvesting kale, lettuce, spinach, broccoli, cabbage, carrots, beets, and fall greens, which sweeten with the chill. Keep row cover handy to push the harvest past the first light frosts. Late September is the time to plant garlic for next year, set out spring-flowering bulbs, divide and move perennials, and sow cover crops or a new lawn. Plant trees and shrubs now while the soil is warm and the rains return. Begin the long autumn cleanup of spent crops.
Zone 3b (high mountains & coldest north): the first hard frost is here, often early in the month, ending the tender crops. Harvest everything tender ahead of frost, dig potatoes, cure squash, and cover or harvest the last greens. The growing season closes earliest here.
Zone 4b (North Country & uplands): frost arrives during September. Watch the forecast, harvest tomatoes and tender crops before the first hard freeze, and keep row cover ready to protect fall greens and extend the season a few weeks.
Zone 5b (interior & lakes region): the first light frost is possible late this month. Keep harvesting and protect tender crops on cold nights with row cover; cool-season crops thrive in the chill, and garlic can be planted late this month for next year.
What's at the Farmers Market
September markets in New Hampshire pivot decisively to fall. Apples arrive in force as the orchard harvest opens — a signature New Hampshire crop, with pick-your-own farms drawing crowds — joined by pumpkins, winter squash, and the last of summer's tomatoes, peppers, eggplant, sweet corn, beans, cucumbers, and melons. Cool-season crops return: broccoli, cabbage, cauliflower, kale, carrots, beets, leeks, potatoes, and crisp fall lettuce and spinach.
Late peaches, raspberries, grapes, fresh-pressed cider, maple syrup, honey, cheeses, mums, and ornamental gourds round out the harvest tables. Choose apples that are firm and heavy with no bruises, and store them cold to keep them crisp for weeks; pick pumpkins and squash with a hard rind and a dry, corky stem and keep them cool and dry, never refrigerated. Buy the last sweet corn the day you'll eat it. The markets are full and colorful, shifting from the abundance of summer to the keeping crops of autumn.
The New Hampshire native plants guide covers what grows here
Night Sky This Month
September brings the autumnal equinox and the return of long, comfortable nights for stargazing. The Summer Triangle still rides high in the early evening, but the autumn constellations climb in the east: the Great Square of Pegasus, the chained figure of Andromeda carrying the faint smudge of the Andromeda Galaxy, and the W of Cassiopeia high in the northeast. The harvest moon rises near the equinox, full and golden on the eastern horizon.
There is no major meteor shower at the peak this month, though the season's first early Orionid and Draconid activity stirs late. The Milky Way still arches overhead in the early night, beautiful from the dark skies of the White Mountains, Lake Umbagog, and the North Country. The cooler, drier air sharpens the views, and aurora chances rise around the equinox on geomagnetically active nights. The printable New Hampshire night-sky guide lists this year's planet positions, harvest moon date, and the best dark-sky windows.
Butterflies & Pollinators
September is monarch month in New Hampshire. The migratory monarch generation streams south through the state, concentrating along the Seacoast and the Connecticut and Merrimack river valleys, pausing to fuel on the goldenrod and aster that blanket the fields. On a good day with northwest winds, dozens or hundreds may drift past a coastal point — one of the most moving wildlife spectacles of the New Hampshire fall, bound for central Mexico.
Other butterflies are still active in the warm afternoons: painted and American ladies, red admirals, common buckeyes in good years, question marks, commas, cabbage whites, clouded and orange sulphurs, and late skippers. The asters and goldenrods are the season's last great nectar source, crucial fuel for the migrants. As the first frosts hit the north, the season winds down from the mountains toward the coast — but the monarch river is the September story worth watching the sky for.
What to plant for them is in the New Hampshire native plants guide
Trees This Month
September is when New Hampshire's legendary fall color begins. The turn starts in the mountains and the North Country and works downhill and south through the month. The earliest and brightest is the red maple, flaming scarlet in the swamps and wet ground by mid-month, joined by sugar maple turning orange and gold, the clear yellow of white and yellow birch and quaking aspen, and the russet of red oak and bronze of American beech.
By late September the high country and the North Country can be at or near peak, drawing leaf-peepers north, while the lowlands and Seacoast are still mostly green. The tamarack begins to yellow in the bogs. The fruit and nut crop ripens: oak acorns and beech nuts drop, feeding wildlife, and white pine sheds its inner needles in a yellow flush. The conifers stay green, anchoring the spectacle. September's color is the opening act of one of the most celebrated autumns in the country, climbing down the state week by week.
The New Hampshire native plants guide covers what grows with them
Weather & Daylight
Across New Hampshire, a typical September day averages a high near 70°F and a low near 47°F, with about 4.0 inches of precipitation — statewide averages from the 1991–2020 U.S. climate normals.
Summer eases into fall, afternoons cooling to 70 and crisper nights near 47, with steady rain returning as the air dries out overhead.
| Average high | 70°F |
|---|---|
| Average low | 47°F |
| Precipitation | 4.0 in |
| Sunrise (mid-month) | 6:25 ET |
| Sunset (mid-month) | 18:58 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).
Next month's version of this page, by email
One short note when New Hampshire's next month turns — what's arriving, blooming, and worth a night outside.
Go deeper with the New Hampshire guides
The complete New Hampshire birding, native-plant, and night-sky references — or the whole year, week by week, in one book.
Same month elsewhere: September in New Jersey · September in New Mexico · September in New York