Rhode Island Nature Guide: September 2026
Data updated: August 2026Sources & method · Corrections
September is the great migration month in Rhode Island — songbirds, raptors, and monarchs stream down the coast, and Block Island becomes one of the Northeast's most celebrated fall migration hotspots. The air cools, the light turns golden, and the harvest peaks with apples, pumpkins, and the last of the summer crops.
Week by week in September
September 3–9
- Fall migration climbs toward its peak; a northwest wind can drop a songbird fallout onto Block Island.
- Monarchs stream south along the coast, gathering at Sachuest Point and the South County dunes on sunny days.
- The best month to plant — set out perennials, trees, and shrubs in the cool, moist soil.
September 10–16
- Raptor migration peaks — sharp-shinned hawks, kestrels, merlins, and peregrines stream down the coast and over Block Island.
- Peak monarch migration; dozens or hundreds may nectar on seaside goldenrod at the coastal points.
- New England asters and goldenrods blaze across fields and roadsides, the season's great banquet.
September 17–23
- The autumn equinox brings balanced days and nights; the harvest moon rises dramatically over Narragansett Bay.
- Tree swallow roosts swirl in tornado-like clouds over the marshes at dusk as migration continues.
- Apples come into full swing — McIntosh, Cortland, and Macoun — with fresh cider and pumpkins.
September 24–30
- Fall color spreads from the swamps to the uplands as the first sugar maples, ashes, and sassafras turn.
- Sparrows pour through the coastal thickets, and the last ospreys depart the bay for South America.
- Plant garlic and spring bulbs, and watch for the first inland frost late in the week.
Birds This Month
September is the climax of fall migration and the finest birding month in Rhode Island. Block Island is the headline event — a legendary migration trap where a northwest wind after a cold front can drop spectacular fallouts of songbirds into the island's thickets: dozens of warbler species (mostly in subtle fall plumage), vireos, thrushes, flycatchers, sparrows, and reliably a few rare western and southern strays that make the island famous among birders.
Raptor migration peaks too: sharp-shinned and Cooper's hawks, American kestrels, merlins, peregrine falcons, ospreys, and broad-winged hawks stream down the coast and concentrate at the points and at Block Island. Shorebirding continues at Trustom Pond and the salt ponds, and offshore, cory's and great shearwaters and other seabirds pass on windy days. Tree swallow roosts swirl in tornado-like clouds over the marshes at dusk.
This month's tip: if you can, get to Block Island after a September cold front and northwest wind — the morning fallout of migrant songbirds and the streaming falcons overhead are among the great birding experiences in New England.
What's Blooming
September is the season of goldenrod and asters in Rhode Island, the great late-season banquet for pollinators and migrating monarchs. Fields and roadsides blaze gold with tall, gray, and rough goldenrods and purple with New England aster, New York aster, and the white sprays of calico and heath asters. Joe-Pye weed, ironweed, and sneezeweed finish in the damp meadows, and the white-flowered boneset hums with insects.
On the coast, seaside goldenrod is at its gilded peak on the dunes and salt-marsh edges — the fuel for the southbound monarchs gathering at the shore. The salt marshes glow with sea lavender and the late pink of salt-marsh fleabane, and the rosa rugosa shows its big scarlet hips against fading foliage. Gardens carry sedum, dahlias, Japanese anemone, chrysanthemums, and the last sunflowers into autumn.
Garden This Month
September is the turn from harvest to autumn in the Rhode Island garden. Keep picking the last of the warm-season crops — tomatoes, peppers, eggplant, beans, and squash — and harvest and cure winter squash and pumpkins as their skins harden. The cool-season fall crops planted in late summer — lettuce, spinach, kale, broccoli, and root vegetables — come into their own as the nights cool and pests fade.
This is the ideal month to plant: cool soil and reliable rain make it the best time to set out perennials, trees, and shrubs, to divide and move spring and summer perennials, and to start a new lawn. Plant garlic late in the month for next summer's harvest, and put in spring-flowering bulbs. Watch for the first frost inland late in the month, and be ready to cover tender plants. Sow cover crops or mulch emptied beds, and start cutting back and cleaning up spent growth.
Zone 6a (inland northwest): the first frost can arrive by late September here, so watch the forecast and be ready to cover tender crops or harvest the last tomatoes and peppers green. Plant garlic and spring bulbs, and sow cover crops on emptied beds.
Zone 6b (inland Rhode Island): harvest winter squash and pumpkins as they harden, keep cool-season greens coming, and plant garlic and bulbs. A protective cover extends the tomato and pepper harvest against an early frost.
Zone 7a (coast & Aquidneck Island): the mild coast often stays frost-free well into October, giving the longest fall harvest. Keep picking summer crops and cool-season greens, and plant garlic, perennials, shrubs, and spring bulbs in the warm soil.
What's at the Farmers Market
September markets in Rhode Island bridge summer and fall, holding peak abundance while autumn crops arrive. The last sweet corn, tomatoes, peppers, eggplant, beans, and summer squash overlap with the new season's winter squash, pumpkins, potatoes, cabbage, broccoli, kale, and greens. Apples come into full swing — McIntosh, Cortland, and Macoun — alongside the last peaches, plums, and the first cider.
The bay's quahogs, oysters, and shellfish continue. Choose apples that are firm, heavy, and unbruised, and store them cold for crispness that lasts for weeks. Pick winter squash and pumpkins with hard skins and intact stems for the longest storage, and keep them somewhere cool and dry. Choose tomatoes heavy and fragrant and keep them at room temperature, and select firm, glossy peppers; use the most perishable greens and berries within a few days.
Night Sky This Month
September brings the autumn equinox and a fine balance of comfortable temperatures and lengthening, darker nights. The Summer Triangle of Vega, Deneb, and Altair still rides high overhead in the evening, with the Milky Way arching through it, while the autumn constellations rise in the east: the Great Square of Pegasus, the W of Cassiopeia, and, beneath them, the Andromeda Galaxy (M31), the most distant object visible to the naked eye, an easy binocular target from a dark coastal site.
There is no major meteor shower this month, so September is for the autumn deep-sky objects and the still-visible summer Milky Way over the ocean. The harvest moon near the equinox rises dramatically over Narragansett Bay on consecutive evenings. The dark skies of the South County beaches and Block Island, with their open Atlantic horizons, remain the state's best.
For exact planet positions and the best viewing windows this month, see the printable Rhode Island night-sky guide for your part of the state.
Butterflies & Pollinators
September is the month of the monarch migration in Rhode Island, one of the most moving wildlife spectacles the state offers. Thousands of monarchs stream south along the coast, and on a good day in mid-September they gather in remarkable numbers at the dunes and points — Block Island, Sachuest Point, and the South County beaches can host dozens or hundreds nectaring on seaside goldenrod and roosting in the shrubs, all bound for the Mexican wintering forests. Alongside them, common buckeyes peak, and American and painted ladies, red admirals, cabbage whites, sulphurs, and late skippers crowd the goldenrod and asters. This is the payoff of every milkweed left standing through the summer. To witness the migration, visit a coastal dune or point on a sunny day after a northwest wind, when the monarchs ride the breeze down the shore.
What to plant for them is in the Rhode Island native plants guide
Trees This Month
September is when Rhode Island's fall color begins in earnest, leading from the wetlands outward. The red maples and tupelos (black gum) of the swamps are already brilliant scarlet and crimson — the state's earliest and most vivid color — and by late month the color spreads to the uplands as the first sugar maples, ashes (deep purple), sassafras (orange and red), and birches (yellow) begin to turn.
The oaks drop their acorns in the great fall mast, feeding the jays, turkeys, squirrels, and deer, and the black cherry, tupelo, and dogwood hang heavy with fruit for migrating birds. On the coast, the pitch pines shed older needles, and the eastern redcedars are blue with berry-like cones. The shortening days and cooling nights are the trigger, and by month's end the Rhode Island landscape is shifting from green to a deepening patchwork of red, orange, and gold.
The Rhode Island native plants guide covers what grows with them
Weather & Daylight
Across Rhode Island, a typical September day averages a high near 74°F and a low near 54°F, with about 4.1 inches of precipitation — statewide averages from the 1991–2020 U.S. climate normals.
A gradual cooldown begins, 74F days and crisper 54F nights, though rainfall picks back up as summer humidity fades.
| Average high | 74°F |
|---|---|
| Average low | 54°F |
| Precipitation | 4.1 in |
| Sunrise (mid-month) | 6:25 ET |
| Sunset (mid-month) | 18:57 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 Rhode Island's next month turns — what's arriving, blooming, and worth a night outside.
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The complete Rhode Island birding, native-plant, and night-sky references — or the whole year, week by week, in one book.
Same month elsewhere: September in South Carolina · September in South Dakota · September in Tennessee