Washington Nature Guide: September 2026
September turns Washington toward autumn — the apple harvest peaks in the Columbia orchards, the larches and aspens begin to gold the eastern slopes, hawks and the first wintering waterfowl return, and the Cascade huckleberry fields blaze crimson on the high slopes.
What to look for this week
- The Skagit flats roar with tens of thousands of wintering Snow Geese, Trumpeter and Tundra Swans, and Bald Eagles line the rivers below the salmon spawn.
- The Quadrantid meteor shower peaks in a brief, sharp burst around January 3 — watch the dark northeast after midnight from the dry country east of the Cascades.
- In the mild Puget lowland, keep harvesting overwintered kale, leeks, and parsnips between rains, and prune dormant apples and roses on a dry day.
- Western hemlock, redcedar, and Douglas-fir carry the gray westside landscape, their trunks furred with moss in the wettest weeks of the year.
Birds This Month
September is a great migration month. Songbirds — warblers, vireos, flycatchers, and tanagers — pour south through the lowlands, and raptors stream along the ridges; the Chelan Ridge and Cascade crest see good hawk flights of Sharp-shinned, Cooper's, and Red-tailed Hawks, Ospreys, and Northern Harriers. Vaux's Swifts stage in spectacular roosts, funneling by the thousands into chimneys at dusk — the Monroe Wagner roost is famous.
Shorebird migration continues on the coast and flats, and the first wintering waterfowl return — American Wigeon, Northern Pintail, Green-winged Teal, and the vanguard of geese reappear on the Skagit and Columbia Basin wetlands. The earliest Snow Geese and Trumpeter Swans arrive late in the month. White-crowned and Golden-crowned Sparrows trickle back into the lowlands to winter, and Varied Thrushes descend from the cooling mountains.
What's Blooming
September's bloom is the late, golden one. Across the lowlands, Douglas aster, goldenrod, pearly everlasting, tansy, and the magenta seed-fluff of spent fireweed color the roadsides and fields. The Himalayan blackberry (naturalized) fruits heavily along every edge. In gardens, dahlias, sedum, and late asters carry the color as the rains return to the westside.
East of the Cascades, the signature fall bloom arrives: rabbitbrush turns the shrub-steppe and roadcuts brilliant gold, alive with late butterflies and bees, joined by gray-green sagebrush coming into inconspicuous flower and lingering buckwheat. In the high country, the wildflower meadows of Rainier and the Olympics have gone to seed, but the huckleberry and mountain ash foliage is turning, beginning the spectacular subalpine fall color of the Cascades.
Garden This Month
September shifts the westside garden into harvest-and-plant mode as the autumn rains return. Bring in the winter squash, pumpkins, the last tomatoes and peppers, beans, and apples and pears, and dig and cure potatoes for storage. The overwintering brassicas, leeks, and fall greens sown in summer are sizing up for the cool months. The wet, cooling weather makes this — alongside October — the Northwest's prime season to plant trees, shrubs, perennials, and a new lawn, since roots establish in moist soil before winter.
Plant garlic and spring bulbs as beds empty, and sow cover crops (crimson clover, fava, rye) on bare ground to protect winter soil. East of the Cascades, the first frosts reach the higher valleys, so harvest tender crops, store the roots and squash, and plant garlic before the eastern ground cools toward winter.
Zone 5b (Cascade foothills & high valleys): first frosts arrive — harvest everything tender before they hit, pull and store root crops and squash, and plant garlic and spring bulbs before the ground cools hard.
Zone 7b (Puget lowland & coastal valleys): harvest winter squash, the last tomatoes, and apples, and plant garlic and cover crops as beds empty. The returning rain means it's a fine time to plant trees, shrubs, and perennials and to sow a fall lawn.
Zone 8a (Puget Sound shore & San Juan Islands): the long season keeps tomatoes and peppers going into the month. Plant garlic and overwintering greens, sow cover crops, and set out hardy trees and shrubs as the autumn rains return.
What's at the Farmers Market
September is the apple month, and Washington is the nation's overwhelming leader. Columbia, Wenatchee, and Yakima valley orchards pour out Gala, Honeycrisp, Cosmic Crisp, Jonagold, Gravenstein, and the first Fuji, alongside Bartlett and Bosc pears, late peaches and plums, fresh table grapes, and concord grapes for juice. Vegetable stalls hold winter squash, pumpkins, tomatoes, corn, peppers, eggplant, and the last Walla Walla onions.
It is also fresh hop season's tail in the Yakima Valley and the start of the fall salmon runs. Choose apples that are firm and heavy for their size and free of soft spots, and store them cold in the crisper away from greens the ethylene will wilt; let firm pears ripen on the counter, since they ripen best off the tree. Markets statewide — Yakima, Wenatchee, Spokane, and the Puget Sound markets — are at a rich autumn peak.
Night Sky This Month
September brings the autumn equinox and the return of longer nights with often-clear skies before the westside rains settle in. The dark-sky destinations stay east of the Cascades — Goldendale Observatory State Park above the Columbia Gorge, Sun Lakes–Dry Falls, and the Methow Valley — where late star parties run under the still-warm desert nights. Westside observers grab the clear early-autumn evenings over the Olympics and Cascades.
The sky transitions: the Summer Triangle still rides high after dark while the Great Square of Pegasus climbs the east, leading Andromeda and its famous galaxy — visible to the naked eye from a dark site and a fine binocular target. The Milky Way still arches overhead in early evening. No major meteor shower peaks this month. For this year's exact planet positions and aurora outlook, see the printable Washington night-sky guide.
Butterflies & Pollinators
September keeps butterflies flying in the warm lowlands and the dry east, though numbers thin as nights cool. The Woodland Skipper is still abundant in westside gardens and fields, joined by late painted and West Coast Ladies, Lorquin's Admirals, Western Tiger Swallowtails, and Cabbage Whites, all nectaring at aster, sedum, and the blooming Himalayan blackberry.
East of the Cascades, the brilliant gold rabbitbrush is a butterfly magnet, drawing coppers, blues, hairstreaks, ladies, and the last monarchs of the Columbia Basin as they begin their thin southward drift toward California and the interior West. California Tortoiseshells and commas seek overwintering shelter. The high-country flight has ended with the meadow bloom, and the mountains are turning to fall color rather than butterflies now.
Trees This Month
September starts Washington's autumn color, most dramatically in the high country and the east. In the Cascade subalpine, the huckleberry, mountain ash, and vine maple turn crimson, orange, and gold beneath the dark mountain hemlock and subalpine fir — the famous early fall display of Rainier, Stevens Pass, and the North Cascades. In the lowlands, bigleaf maple begins to yellow and black cottonwood turns gold along the rivers.
East of the Cascades, the signature autumn tree begins to turn: the deciduous western larch, alone among Northwest conifers, starts to gold the high eastern slopes (peaking in October), while the quaking aspen groves of the Okanogan and the riverside cottonwoods light up yellow. The evergreen backbone — Douglas-fir, western redcedar, western hemlock, and ponderosa pine — holds green as ever, now dropping their ripe cones.
Go deeper with the Washington guides
The complete Washington birding, native-plant, wildflower, and night-sky guides — or the whole year in one bundle.
Same month elsewhere: September in West Virginia · September in Wisconsin · September in Wyoming