Minnesota Nature Guide: September 2026
Data updated: August 2026Sources & method · Corrections
September is the great migration month and the start of Minnesota's spectacular fall — the hawk flights stream down the North Shore, the monarchs funnel south, and the first fall color ignites the aspens and maples of the north. The air turns crisp, and the whole landscape begins its turn toward winter.
Week by week in September
September 3–9
- Hawk Ridge above Duluth peaks for broad-winged hawks — thousands stream down the Lake Superior shore in great spiraling kettles on north winds.
- The monarch migration funnels south along the North Shore, often in impressive numbers, the most dramatic butterfly event of the year.
- Pick tomatoes, peppers, and squash ahead of the first frost (earliest in the north), and plant garlic and spring-flowering bulbs.
September 10–16
- Hawk Ridge migration continues with eagles, ospreys, and falcons, while warblers, vireos, and sparrows pour through in the songbird flood.
- New England aster and the last goldenrod offer the final, critical nectar to migrating monarchs and the season's last bees.
- Fall color ignites in the North Woods — aspen and birch turn gold and the sugar maples flame along the North Shore drives.
September 17–23
- Sandhill cranes begin massing for fall staging, and the last common loons depart the cooling northern lakes.
- The fall equinox arrives around September 22, finally returning the longer nights — a favorable period for catching the northern lights.
- North Shore and Arrowhead fall color peaks — Highway 61 and the Gunflint Trail blaze with maple, aspen, and birch.
September 24–30
- Sparrows pour through — white-throated, white-crowned, and fox sparrows fill the brushy edges, and dark-eyed juncos arrive at feeders.
- Apple season is in full swing — Honeycrisp, SweeTango, and Cortland at the orchards — and hand-harvested wild rice arrives from northern lakes.
- Harvest frost-sweetened kale, carrots, and Brussels sprouts; finish planting garlic and bulbs as the first hard frosts arrive.
Birds This Month
September is one of Minnesota's two best birding months, defined by fall migration. The signature spectacle is Hawk Ridge above Duluth, where tens of thousands of raptors — broad-winged hawks in their massive 'kettles,' along with sharp-shinned hawks, bald eagles, ospreys, kestrels, and harriers — stream down the Lake Superior shore on north winds, peaking in mid-September. It is one of the premier hawk-watching sites in North America.
Songbird migration is in full flood: warblers (in tricky fall plumage), vireos, thrushes, sparrows, and the last ruby-throated hummingbirds moving through. Common nighthawks stream south early in the month, and huge mixed flocks of blackbirds swirl over the marshes. On the lakes, common loons gather and begin staging for departure, and waterfowl numbers build. By late September, sandhill cranes begin massing for their fall staging, and the first juncos and winter sparrows arrive. Almost every day brings something new — it's a thrilling, fast-moving month for any birder.
What's Blooming
September is the last great flush of wildflowers, and asters and goldenrod carry the show. The prairies, roadsides, and old fields glow with the purple of New England aster, smooth aster, sky-blue aster, and the white of heath and panicled asters, set against the fading gold of late goldenrod. These are the final, critical nectar sources for migrating monarchs and the season's last bees.
The prairies still hold late sunflowers, gentians (including the lovely bottle gentian), ironweed, and the seed heads of the summer's coneflowers and blazing star, which now feed the goldfinches. In the wetlands, the cardinal flower and great blue lobelia finish, and turtlehead blooms in the marshes. Garden asters, sedums (now russet), mums, and the last dahlias and zinnias hold on until frost. By late September a hard frost ends the bloom across much of the state, especially in the north — so the early-month aster-and-goldenrod display is the season's grand finale.
Garden This Month
September is harvest's grand finale and the start of putting the garden to bed. The first frost looms — early-to-mid September in the north, late September into October in the south — so the priority is bringing in the tender crops: pick all the tomatoes, peppers, eggplant, squash, melons, and beans ahead of a hard freeze, and ripen green tomatoes indoors. The hardy crops actually improve now: kale, chard, carrots, beets, parsnips, Brussels sprouts, and leeks sweeten after light frosts and can stay in the ground.
It's prime time to plant garlic for next summer and to set out spring-flowering bulbs (tulips, daffodils, alliums, crocus) before the ground freezes. Sow a cover crop or spread shredded leaves on emptied beds, divide and plant perennials while the soil is still warm, and water trees and shrubs deeply going into fall. Leave seed heads and stems standing for the birds and overwintering pollinators where you can — the messier fall garden is the better one for wildlife.
Zone 3b (far north & Iron Range): the first frost typically arrives in early-to-mid September here, ending the warm-season garden. Harvest everything tender ahead of it, cover late crops if you want a few more days, and begin cleanup, garlic planting, and mulching for the long winter.
Zone 4b (most of the state): the first frost usually comes late in the month. Harvest tomatoes, peppers, and squash ahead of it (green tomatoes ripen indoors), keep harvesting hardy greens and roots that sweeten in the cold, and plant garlic and spring bulbs.
Zone 5a (Twin Cities metro & southeast): the warmest zone often escapes frost until early-to-mid October, extending the harvest. Keep picking, plant garlic and spring-flowering bulbs, sow a cover crop on emptied beds, and protect tomatoes from the first light frosts to stretch the season.
What's at the Farmers Market
September markets shift from high summer to the rich harvest of fall. Apples take center stage — Minnesota's famous Honeycrisp (a University of Minnesota release) ripens in September, along with SweeTango, Zestar, Cortland, and Haralson — and the orchards open for picking. Winter squash in every shape arrives (butternut, acorn, delicata, kabocha), along with pumpkins, the last of the sweet corn and tomatoes, and a flood of potatoes, onions, carrots, beets, cabbage, peppers, broccoli, cauliflower, leeks, and cooking greens.
The season's specialty appears now: hand-harvested wild rice ('manoomin') from the northern lakes. Choose Honeycrisp and other apples that are heavy, firm, and richly colored, and store them cold for months of crisp eating; pick winter squash with a hard, dull rind and a dry stem, and cure them in a warm, dry spot before storing cool. With the harvest at its richest and the weather crisp, September markets are among the best of the year.
Night Sky This Month
September brings the fall equinox around September 22, when the nights finally grow longer than the days again and darkness returns earlier — a relief for stargazers after the short summer nights. The summer constellations are still up: the Summer Triangle rides high after dark, and the Milky Way arches overhead, its core sinking toward the southwest as the season turns. In the east, the great square of Pegasus and the constellation Andromeda rise, carrying the Andromeda Galaxy — the most distant object visible to the naked eye from a dark site.
Equinox periods are favorable for the aurora borealis, and September is one of the better months to catch the northern lights from Minnesota's dark north country — the Boundary Waters, Voyageurs, and the Arrowhead. The cool, clear, bug-free nights make this one of the most comfortable stargazing months of the year. The printable Minnesota night-sky guide lists this year's planet positions and aurora outlook for your part of the state.
Butterflies & Pollinators
September is the month of the great monarch migration through Minnesota — the single most dramatic butterfly event of the year. The 'super generation' of monarchs streams south, often funneling in impressive numbers along Lake Superior's North Shore and concentrating at points and shorelines, fueling up on the goldenrod and aster as they go. Watch for them flying steadily southward on warm days with north winds, and gathering in roosting clusters in sheltered trees at night — the leading wave passes through the first half of the month.
Other late-season butterflies are still about while the warmth and flowers last: painted ladies, red admirals, common buckeyes, clouded and orange sulphurs, the last fritillaries, and the overwintering mourning cloaks and commas feeding up before they tuck away for winter. The goldenrod and aster blooming now are the last great nectar source. A hard frost ends the butterfly season across much of the state by late September, especially in the north.
What to plant for them is in the Minnesota native plants guide
Trees This Month
September is when Minnesota's legendary fall color ignites, sweeping from the Canadian border southward through the month. The North Woods lead: the quaking aspen and paper birch turn brilliant gold across the Arrowhead and the Iron Range, and the sugar maples and red maples flame orange and scarlet — the North Shore drives (Highway 61, the Superior National Forest, the Gunflint Trail) reach peak color from roughly mid-to-late September.
Color builds southward into the Twin Cities and the Big Woods by late September and early October. The sumac blazes red along the roadsides, basswood and birch turn yellow, and the oaks begin their slower russet and bronze turn. In the bogs, the tamaracks are still green but will soon glow gold. Trees are also dropping their crop — acorns, walnuts, and hickory nuts fall, feeding the squirrels, deer, and jays stocking up for winter. It's the most beautiful month of the Minnesota tree year.
The Minnesota native plants guide covers what grows with them
Weather & Daylight
Across Minnesota, a typical September day averages a high near 70°F and a low near 47°F, with about 3.1 inches of precipitation — statewide averages from the 1991–2020 U.S. climate normals.
Gently cooling, mornings crisp again as the sharpest summer heat fades into golden, mild afternoons.
| Average high | 70°F |
|---|---|
| Average low | 47°F |
| Precipitation | 3.1 in |
| Sunrise (mid-month) | 6:54 CT |
| Sunset (mid-month) | 19:30 CT |
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 (CT).
Next month's version of this page, by email
One short note when Minnesota's next month turns — what's arriving, blooming, and worth a night outside.
Go deeper with the Minnesota guides
The complete Minnesota birding, native-plant, and night-sky references — or the whole year, week by week, in one book.
Same month elsewhere: September in Mississippi · September in Missouri · September in Montana