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.

The warm color gives Seattle's summer-grey backdrop deliberate contrast and carries directly into a Capitol Hill dinner.

The lighter daytime rotation for Alki, Bainbridge, or a warm 25°C / 77°F neighborhood afternoon.

Wear it open over the tank on ferry decks, at Kerry Park sunset, and in over-cooled restaurants.

The warm-afternoon base layer, clean enough for the Market and compact enough for a ferry-day bag.

More intentional than athletic shorts and dark enough to handle a full market-and-ferry day.

The Capitol Hill dinner alternative keeps airflow while covering the evening temperature drop.

Puget Sound breeze cools evenings to 14°C / 57°F, and this rolls into the bag without bulk.

The structured evening layer shown in the illustrated dinner look; enough warmth without carrying rain gear.

The easy summer shoe for the Market and ferry, with more support than a flip-flop.

Use these for Discovery Park, Volunteer Park, and any day with sustained walking.

The rounded basket holds a ferry picnic and a cover-up and reads lighter than a commuter bag in August.

Alki Beach, Lake Washington, kayaking, and Green Lake all peak in August.

Loose enough for the beach and useful as a second ferry layer when the breeze picks up.

Seattle August UV is higher than visitors expect, especially on the water.

A low-key PNW sun layer for the market, ferry deck, and park.

Water reflection and long dry days make reapplication essential even when the air feels cool.

Keep one in the bag for the occasional BC, eastern Washington, or California smoke day.

The compact dinner bag in the illustrated evening look, polished without fighting Seattle's smart-casual register.
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.