Seattle in August: 25°C / 77°F afternoons, 14°C / 57°F mornings, 5 rain days, 281 sunshine hours — secret best month alongside July.
August is Seattle's best-kept travel secret alongside July. NOAA climate data show afternoons at 25°C (77°F), mornings at 14°C / 57°F, just 5 rain days and 25mm rainfall, and 281 hours of sunshine — only slightly less than July. The Mediterranean-feel dry summer continues through August; fire smoke from BC or California can occasionally push AQI into unhealthy ranges on unlucky days, but most Augusts are uneventful. Seafair hydroplane races, Bumbershoot (late August-early September), and Pacific Northwest ferry day trips to Bainbridge, Vashon, or the San Juans dominate local plans. The Seattle August uniform finally lets go of the rain shell as daily gear (pack one for emergencies but don't wear it daily); leans into Birkenstocks, a rust brown cutout midi, black floral shorts, linen trousers, clean sneakers. Mornings still start at 14°C / 57°F with Puget Sound breeze — cream crewneck sweatshirt in the bag daily. Tech culture continues to keep dress codes smart-casual most places.
The Mediterranean-feel dry summer continues through August — fire smoke from BC or California can occasionally push AQI into unhealthy ranges on unlucky days.

August finally rewards summer dresses in Seattle. The rust brown cutout adds the bright-against-gray contrast PNW locals deliberately wear to push back against the 9 months of overcast — a different colour story than July's linen midi but the same silhouette logic.

Tank alone for warm 25°C / 77°F afternoons; the light blue striped button-down open over it for ferry rides, Kerry Park breezy sunsets, AC restaurants. The full button-down sits cleaner over a tank than July's cropped striped version did.

Black floral shorts read more dressed-up than July's plain high-waisted black ones — sit-down bars in Ballard accept them where athletic shorts read out-of-place. Linen trousers for Capitol Hill dinners.

Still needed. Puget Sound breeze cools evenings to 14°C / 57°F. The crewneck sweatshirt rolls into the bag without bulk; June's heavier cardigan stays at home.

Birkenstocks are peak in August. Sneakers for Discovery Park or Volunteer Park long walks.

Backpack for urban days + tech-casual spots. The woven straw basket bag (rounded silhouette over July's flat tote) holds a ferry-picnic six-pack and a swimsuit cover-up cleanly for Alki, Bainbridge, or Vashon beach days.
Tank · black floral print shorts · Birkenstocks · woven straw basket bag · cap. Farmers Market at U District, ferry to Bainbridge Island.
Rust brown cutout midi dress · denim jacket · clean sneakers · structured small bag. Dinner at Canon (Capitol Hill) or Rupee Bar (Ballard).
Per NOAA climate data: average daily high is 25°C (77°F), low is 14°C (57°F). Only 5 rain days with 25mm rainfall. 281 hours of sunshine. One of the driest, sunniest months — similar to July but slightly shorter daylight and occasional BC/California fire smoke risk.
Among the best months. Dry, mild, sunny, long evenings. Seafair (hydroplane races + Blue Angels), Bumbershoot festival late-August, peak ferry day-trip season (Bainbridge, Vashon, San Juans). Trade-offs: peak tourism, higher hotel prices, occasional fire smoke days.
Occasionally. Fires in British Columbia, eastern Washington, or Northern California can push smoke west-to-east, dropping AQI to unhealthy ranges for 3-7 days at a time. Check AirNow.gov daily. Pack 2-3 N95 masks for backup. On smoke days, indoor alternatives (Chihuly Garden, Museum of Pop Culture, Pike Place indoor areas) work.
Not as daily gear. 5 rain days per month and 25mm rainfall total — less than Paris, London, or Lisbon. If staying 3-4 days, you can reasonably skip it and rely on a cardigan. If staying longer, pack a compact rain shell for 1-2 rainy afternoons.
Layers that handle cool Puget Sound breeze (15-17°C / 59-63°F on ferry deck even in 25°C / 77°F sun). Black floral print shorts or linen trousers, tank + light blue striped button-down, denim jacket, Birkenstocks or clean sneakers, woven straw basket bag with picnic + water. Cream crewneck sweatshirt in the bag for the ride home (golden hour on the ferry is cool). Skip heels — ferry decks are metal and slippery.