August is late summer in Delaware — hot and humid, but already tilting toward fall. Southbound shorebirds crowd the bay-shore mudflats, the markets are at their fullest, and the first cool fronts bring the year's clearest, most star-filled nights and the Perseid meteors.
Week by week in August
July 30 – August 5
- Southbound shorebirds crowd the Bombay Hook impoundments — semipalmated, least, and pectoral sandpipers and dowitchers in worn plumage.
- The first goldenrods open and joe-pye weed and ironweed raise their dusty-rose and purple heads in the wet meadows.
- Sweet corn, watermelons, tomatoes, and peaches are all in full flood at the summer market's peak.
August 6–12
- The Perseid meteor shower peaks around August 12, the best of the year, sending bright fireballs across the dark sky after midnight.
- Monarchs nectar on the first goldenrod as the southbound drift toward the coast begins in late summer.
- The first southbound warblers trickle through the woods, often quiet and in confusing fall plumage.
August 13–19
- Fall shorebird diversity peaks at Bombay Hook — patient study of the sandpiper flocks turns up rarities among the masses.
- The key fall-planting window — sow spinach, lettuce, and brassicas and set out fall broccoli and cabbage transplants.
- The first early apples and Asian pears appear as the late blueberries and blackberries finish.
August 20–26
- Skippers are at their peak and cloudless sulphurs drift up from the south as the monarch buildup gathers.
- Saltmarsh fleabane hazes the marsh edges purple and the groundsel tree sets bud for fall.
- Purple martins stage in large roosts and chimney swifts gather before departing south.
August 27 – September 2
- Cold fronts trigger the first autumn raptor flights and songbird waves concentrating at Cape Henlopen's point.
- Goldenrods and the first asters surge across the fields and dunes, the critical nectar for the migrating monarchs.
- Late summer and early fall overlap — tomatoes, melons, and peaches beside the first winter squash and apples.
Birds This Month
August is dominated by southbound shorebird migration in Delaware. The impoundments and mudflats of Bombay Hook and Prime Hook fill with returning waders — semipalmated, least, western, pectoral, and stilt sandpipers, short-billed dowitchers, greater and lesser yellowlegs, and large flocks of semipalmated plovers — many in worn breeding plumage, refueling on their way south. This is a premier time to study fall shorebirds, and rarities turn up among the masses.
Songbird migration also begins: the first southbound warblers — yellow, American redstart, black-and-white, and worm-eating — trickle through the woods, often quiet and in confusing fall plumage. Purple martins stage in large roosts before departing, chimney swifts gather, and the marsh egrets and herons disperse widely. Ospreys begin drifting south late in the month. Ruby-throated hummingbirds work the cardinal flower and jewelweed.
This month's tip: visit Bombay Hook on a falling tide and scan the exposed mud carefully — August is the peak of fall shorebird diversity, and patient study of the sandpiper flocks is some of the most rewarding birding of the Delaware year.
What's Blooming
August begins Delaware's long late-summer-into-fall bloom. The tall composites take over the meadows and roadsides: the first goldenrods open in waves, joe-pye weed and ironweed raise their dusty-rose and deep-purple heads in the wet ground, and boneset, sneezeweed, wingstem, and tickseed sunflower brighten the damp edges. Cardinal flower still flares scarlet along the streams, and jewelweed hangs its orange trumpets in the wet woods.
In the tidal marshes of Bombay Hook and Prime Hook, the rose mallow finishes its big pink hibiscus bloom, the saltmarsh fleabane hazes the marsh edges purple, and the groundsel tree sets bud for fall. On the dunes at Cape Henlopen, the seaside goldenrod begins to color and the beach heather holds its low gold. The shift from summer to fall flowering is underway, the nectar that will fuel the coming monarch migration just coming on across the First State.
Garden This Month
August is the pivot from summer harvest to fall planting in the Delaware garden. The summer crops are at full tilt — tomatoes, peppers, corn, beans, cucumbers, squash, eggplant, and the first watermelons and cantaloupes — and the work is keeping up with the picking and preserving. At the same time, this is the key window for the fall garden: sow spinach, lettuce, arugula, radishes, turnips, kale, collards, carrots, and beets, and set out transplants of fall broccoli, cabbage, cauliflower, and Brussels sprouts for an autumn and early-winter harvest in the long First State season.
Heat and humidity still rule, so water the newly seeded fall crops faithfully — they need consistent moisture to germinate in the warm soil, and a little shade cloth helps. Pull spent summer plants as they fade, but keep tomatoes and peppers producing into fall. Watch for the late-summer surge of stink bugs, spider mites, and fungal disease in the humid air, and keep harvesting beans and squash young. Order garlic for fall planting and spring bulbs for autumn. The garden straddles two seasons at once now.
Zone 7a (northern New Castle County): the shorter northern season means now is the moment for fall planting — sow spinach, lettuce, radishes, turnips, and a last quick round of bush beans, and set out fall broccoli, cabbage, and kale transplants before the days shorten.
Zone 7b (Kent, Sussex, and the coast): the long lower-county season gives more room — keep sowing fall greens, carrots, beets, and brassicas, and even a late round of summer squash and beans can mature before the mild coastal first frost.
What's at the Farmers Market
August keeps the Delaware market at its summer peak. Sweet corn, watermelons, cantaloupes, vine-ripe tomatoes, and heritage peaches are all in full flood, joined by lima beans, green beans, peppers, eggplant, summer squash, cucumbers, okra, and the first winter squash and potatoes. The late blueberries and blackberries finish, and the first early apples and Asian pears appear toward month's end.
From the Delaware Bay, blue crabs are at their summer best — choose live, lively crabs that feel heavy for their size, keep them cold and damp under wet burlap, and cook them the day you buy. Choose corn with bright husks and plump kernels for same-day use, melons heavy for their size with a creamy ground spot, and peaches that are fragrant and give slightly. Pick okra pods small and tender and tomatoes heavy and fragrant, storing them at room temperature. The Delaware stands are at their generous late-summer fullness, the heritage crops all on the table at once.
Night Sky This Month
August brings the year's most popular night-sky event and the first crisp nights. The Perseid meteor shower peaks around August 12, one of the best and most reliable showers of the year, sending swift, bright meteors and frequent fireballs across the sky after midnight as Earth crosses the debris of Comet Swift-Tuttle. From a dark Delaware site under a moonless sky, dozens an hour are possible. The Summer Triangle rides overhead and the Milky Way still arches richly through it toward Sagittarius in the south.
As the month wears on, the first cool, dry fronts clear the summer haze and deliver some of the year's most transparent skies. Watch Scorpius and the galactic center sink in the southwest while the autumn stars of Pegasus climb in the east. Seek the darkest skies at Cape Henlopen and the lower Sussex coast, looking south and east over the bay and ocean away from the inland glow.
Exact planet positions and this year's exact Perseid peak timing vary year to year — the printable Delaware night-sky guide carries the current dates and viewing details for your region.
Butterflies & Pollinators
August is a peak butterfly month in Delaware, and the start of the great monarch buildup. The meadows are alive with monarchs nectaring on the first goldenrod and joe-pye weed, the late-summer generation that will become the migrants — by late August the southbound drift toward the coast is beginning. The swallowtails remain strong — eastern tiger, spicebush, black, and the late-summer giant swallowtail wandering north — and great spangled fritillaries, common buckeyes, red admirals, painted ladies, and viceroys crowd the flowers.
The skippers are at their dizzying peak across the grasslands — silver-spotted, fiery, sachem, Zabulon, and a host of small grass skippers — and the sleepy orange and cloudless sulphur drift up from the south into the open fields. The common buckeye numbers swell with coastal migrants. Now is the time to keep nectar-rich late flowers blooming — goldenrod, ironweed, and zinnias — to fuel the monarchs and the swelling late-summer fauna gathering before fall.
What to plant for them is in the Delaware native plants guide
Trees This Month
Delaware's trees hold their deep summer green through August, but the first faint signs of fall creep in. Stressed and early-turning species drop scattered leaves: tulip trees yellow and shed in the heat, black gum shows the first flares of scarlet that make it Delaware's earliest reliable fall color, and the sassafras begins to color at the edges. The flowering dogwoods set their clusters of red fruit, ripening for the migrating birds.
The fruit and nut season advances: black walnuts drop their green husks, hickories and oaks swell this year's acorns, and the persimmons hang green toward their fall ripening. American holly, the state tree, carries its hardening berries toward winter red. The loblolly pines of Sussex and the bald cypress of Trap Pond stand full and dark. The canopy is still thick and shading, but the wildlife is already harvesting the year's mast, and the very first hints of the turn are visible in the wet woods.
The Delaware native plants guide covers what grows with them
Weather & Daylight
Across Delaware, a typical August day averages a high near 85°F and a low near 66°F, with about 4.7 inches of precipitation — statewide averages from the 1991–2020 U.S. climate normals.
Hazy, humid days near 85 barely cool into the mid-60s at night, thick air and frequent storms lingering through the month.
| Average high | 85°F |
|---|---|
| Average low | 66°F |
| Precipitation | 4.7 in |
| Sunrise (mid-month) | 6:15 ET |
| Sunset (mid-month) | 19:59 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 Delaware's next month turns — what's arriving, blooming, and worth a night outside.
Go deeper with the Delaware guides
The complete Delaware birding, native-plant, and night-sky references — or the whole year, week by week, in one book.
Same month elsewhere: August in Washington, D.C. · August in Florida · August in Georgia