Seattle weather in September
Monthly temperatures, rain, humidity, what to wear and what to pack — 2024–2025 historical average
Seattle September weather at a glance
In September, Seattle averages 16.7°C, with typical highs of 21.3°C and lows of 13.4°C. The historical average is 6 wet days and 78% humidity.
Seattle September temperature & humidity
Seattle September rain & wet days
Pack a compact umbrella. Keep an indoor stop available between outdoor activities.
What to wear in Seattle in September
T-shirts or long sleeves with one light outer layer should be comfortable.
- DaytimeLong sleeves and a light jacket · average high 21.3°C
- Morning & eveningLong sleeves with a jacket or cardigan · average low 13.4°C
- FootwearComfortable walking shoes; quick-dry footwear for rainy days.
Packing essentials
Coupang affiliate links · We earn a commission on purchases. Products are sold on the Korean Coupang store.
Seattle September sunrise & sunset times
2026 September · Local time (America/Los_Angeles)
| Date | Sunrise | Sunset | Daylight |
|---|---|---|---|
| 2026-09-01 | 06:28 | 19:49 | 13h 21m |
| 2026-09-15 | 06:47 | 19:21 | 12h 34m |
| 2026-09-30 | 07:07 | 18:50 | 11h 43m |
For sunset photos, arrive before the listed sunset time. Clouds, mountains and buildings can change when the sun becomes visible or disappears.
Calculated for the city coordinates with daylight saving applied. SunCalc · tz-lookup
Seattle travel updates
Watch live CCTV
- I-5 / Mercer, SeattleSeattle City · Updated images
Check the camera timestamp at the source.
Today’s weather and forecast
Check temperature, rain and wind in Windy.
Forecast · Windy. Monthly averages are in the Temperature section.
Seattle news search
Search for recent news and check publication dates before you travel.
Seattle city map
This map shows the city area, not a specific meeting point.
Seattle travel essentials
Popular MyRealTrip products · city search, sorted by sales · Product names are in Korean.
- Travel SIM card
[미주 유심] T-mobile 5~90일 무제한공항 수령 미국/캐나다/멕시코Book now ↗ - Travel SIM card
[시티트립 미국 uSIM] 라이카 5~30일 무료국제전화 *미국/하와이Book now ↗ - 미국 전자비자 ESTA 발급 대행Book now ↗
- Travel eSIM
미국 이심 eSIM 뉴욕 LA 티모바일 매일 500MB 무제한 1일 유심사 알림톡Book now ↗ - Travel SIM card
[미국유심] 미국 메이저 통신사 버라이즌 미국내 통화 데이터 무제한 30일 미국번호로 개통Book now ↗
Explore with Klook
Klook.comAffiliate widget · We may earn a commission on bookings.
Seattle hotel search · Trip.com
Search hotels by destination, dates and number of guests. The Trip.com widget is in Korean.
Affiliate widget · A qualifying booking may earn us a commission. Trip.com may use cookies in this search widget.
Best months to visit Seattle
Bar height shows our simple weather-comfort score, not a safety rating; colour shows temperature.
September weather by year
Daily weather in 2025
Daily high and low temperatures; blue labels show precipitation
Frequently asked questions
What is Seattle weather like in September?
In September, Seattle averages 16.7°C, with typical highs of 21.3°C and lows of 13.4°C. The historical average is 6 wet days and 78% humidity. Our weather-comfort rating for this month is excellent.
Does it rain a lot in Seattle in September?
There are about 6 wet days in September. A compact umbrella is still useful.
What should I wear in Seattle in September?
T-shirts or long sleeves with one light outer layer should be comfortable.
What are the best months to visit Seattle?
Recent weather data rates June, July, August, September among the more comfortable months.
Where can I check Seattle weather in September in real time?
Check local webcams for the view right now and a local weather service for today’s forecast. Monthly temperatures here are historical averages.
What time are sunrise and sunset in Seattle in September?
On 2026-09-15, calculated sunrise is 06:47 and sunset is 19:21 in local time (America/Los_Angeles). Times vary by date and terrain.
Seattle weather by month
More Americas destinations in September
Open-Meteo (CC BY 4.0) · 2024–2025 historical data, aggregated and rounded by this site. Not a forecast or long-term climate normal. Calculation method and limitations