New Hampshire Nature Guide: September 2026
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.
What to look for this week
- Feeders are at their winter peak — black-capped chickadees, nuthatches, and cardinals work the seed, with purple finches, redpolls, and siskins possible in a northern-finch irruption year.
- The Quadrantid meteor shower peaks in a short, sharp burst around January 3; watch the northeast after midnight from a dark White Mountains site.
- A planning week — order seeds early, especially the short-season varieties North Country and high-elevation gardens depend on, before they sell out.
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.
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.
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.
Go deeper with the New Hampshire guides
The complete New Hampshire birding, native-plant, wildflower, and night-sky guides — or the whole year in one bundle.
Same month elsewhere: September in New Jersey · September in New Mexico · September in New York