Early autumn · Weather & things to do
Seattle in September
Seattle cools off: highs slip to 69°F (21°C), from 75°F in August, with lows of 52°F (11°C) and about 2.3 in (58 mm) of rain.
At 90/100 for comfort (2nd of 12), it's one of the best months to visit.
- Avg high
- 69°F (21°C)
- Avg low
- 52°F (11°C)
- Rain
- 2.3 in (58 mm)
- Humidity
- 78%
- Cloud cover
- 53%
- Daylight
- ~12 h 19 min
- Comfort score
- 90/100 · Great
What September feels like
Expect mild afternoons around 69°F (21°C), good for long walks.
Nights cool to an average low of 52°F (11°C).
About 2.3 in (58 mm) of rain falls in a typical year's September.
Plan around September
September is one of Seattle's best months on the climate data.
- Last dry month before the rain picks up: October brings 4.9 in (125 mm).
- Last of the best-scoring months: by October, the score drops to 69/100.
- Comfort holds steady from August (90 → 90/100).
- September sits inside the Jun – Sep window our Pacific Northwest route recommends.
- September sits inside the May – Sep window our Puget Sound Islands route recommends.
- Our Seattle, Snoqualmie Pass & Leavenworth route is planned for Late Nov – Dec, a window set by the holiday season rather than the weather — September falls outside it.
What to pack for September
- A warm layer for eveningslows near 52°F
- Comfortable walking shoesmost places below are best reached on foot or with short walks
What to do in Seattle in September
With conditions on your side, the picks below favor time outside.
Ivar's Acres of Clams
Waterfront seafood house on Pier 54, serving clam chowder and fish and chips since 1946.
Why now September scores 90/100 for comfort, good conditions for being outside.
Kerry Park
Small Queen Anne park with the classic skyline view of the Space Needle and, on clear days, Mount Rainier.
Why now Highs near 69°F and 2.3 in of monthly rain make this an easy outdoor pick.
Pike Place Chowder
Award-winning New England clam chowder stall in Post Alley.
Why now One to do outside while the weather is on your side.
Hiram M. Chittenden Locks
Ballard Locks move boats between Lake Washington and Puget Sound; fish ladder windows show migrating salmon.
Why now Our curated notes say it's best Jul–Sep.
Pacific Northwest Ballet's Nutcracker at McCaw Hall
Pacific Northwest Ballet's annual Nutcracker, staged at McCaw Hall at Seattle Center from late November through late December.
Discovery Park
Seattle's largest park: bluff meadows, forest loop trail and a beach walk to West Point Lighthouse.
Nearby in September
- Bainbridge Island in September~9 mi · highs 69°F, 2.3 in rain · similar daytime temperatures, about as wet
- Snoqualmie Pass in September~45 mi · highs 62°F, 3.0 in rain · 4°C (7°F) cooler by day, wetter
- Olympic NP in September~61 mi · highs 53°F, 3.4 in rain · 9°C (16°F) cooler by day, wetter
- San Juan Island in September~71 mi · highs 65°F, 2.0 in rain · 2°C (4°F) cooler by day, about as wet
These averages also cover Pike Place Market & Waterfront and Seattle Center & Queen Anne.
NASA POWER 2001–2025 monthly averages on a ~50 km grid. Comfort scores weigh temperature, rain, humidity and cloud: see how we score each month. Check a forecast before you go.
Seattle in September: quick answers
Is September a good time to visit Seattle?
Yes. On the climate data it's one of the best months, scoring 90/100. Expect highs of 69°F (21°C) and 2.3 in (58 mm) of rain. September is inside the Jun – Sep window our Pacific Northwest route recommends.
How hot is Seattle in September?
Average highs are 69°F (21°C) and average lows 52°F (11°C), making it the 3rd-warmest month by daytime highs.
Does it rain a lot in Seattle in September?
Not much: about 2.3 in (58 mm) of rain falls across September on average, the 4th-driest month of the year. The annual total is about 48.4 in (1230 mm).
What should I pack for Seattle in September?
Bring a warm layer for evenings (lows near 52°F) and comfortable walking shoes (most places below are best reached on foot or with short walks).
Routes in season in September
- Pacific Northwest Jun – Sep
- Puget Sound Islands May – Sep
Planning Seattle in September?
Share this September plan with your group, poll everyone on dates and keep the packing list in one place.