Updated 14 Sep 2026 · recomputed nightly
Is September 2026 a good month to visit Seattle?
Busy — the typical September day in Seattle is busier than 69% of its year.
If you are coming for something that only happens in September, that is the trade. If not, February is quieter.
Calm · Lively · Busy · Packed rank a day against Seattle's own year — not a headcount.
This month's verified events: Labor Day (7).
September is one of Seattle's busiest months: mild and wet, around 21°C / 70°F with rain on about 11 days, and Busy on 8 of 17 days. (Our forecast covers 14–30 September — the rest of September is beyond the current window.)
No. The typical September day in Seattle is Busy, and 11 of the 17 days in our window run Busy or Packed, so most days feel crowded. Expect around 21 °C by day, with rain on about 11 days. Public holidays in China add to it. Cruise ships call on 14 of the 17 days, 3 at once on Monday 21 September. For similar weather with fewer people, come in October. The crush is at the Overlook Walk stairs; the quiet is at Pioneer Square when nothing is on. The calmest day is Wednesday 16 September, the busiest Wednesday 30 September.
In short, a hard sell — heavy crowds without the best of the weather.
Among the 12 months we forecast for Seattle, September ranks 5th for crowd pressure. Its heaviest day is Wed 30 Sep, busier than 99% of the year; its lightest is Wed 16 Sep at 55%.
⚠︎ Weekends run heavy — the 19th, 20th, 26th and 27th all sit Busy or Packed. If your dates can flex, a midweek arrival is the single easiest win.
Preparing pays off in a month like this: timed-entry tickets and pre-booked tours turn the queue time into sightseeing time. see the options →
Pack for wet first — rain on 11 of 30 days.
A folding one lives in the day bag and weighs nothing.
See umbrellas →
Wet stone is the thing to plan around in a month this wet.
See walking shoes →
How busy is Seattle in September?
The busiest days are the 19th, 21st, 28th and 30th, and 7 more. Away from those, most days sit Lively. The calmest stretch is the 22nd–24th.
Cruise ships are in port on 14 of 17 days; the heaviest is Mon 21 Sep, 3 ships in at once. Those mornings fill the squares first — start early, or save them for indoors.
The month is not one thing: its lightest day sits at 55% of the year and its heaviest at 99%, so where you land inside it matters. All three Mondays run Busy or Packed. Daylight runs about 12 hours.
Either side of it, August is busier still and October is much calmer.
Weekends run heavy — the 19th, 20th, 26th and 27th all sit Busy or Packed. If your dates can flex, a midweek arrival is the single easiest win.
Mon 14 Sep Busy busier than 75% of days here · ⚓2
- Anthem of the Seas — guest capacity 4,168 06:00–16:00
- MSC Poesia — guest capacity 2,550 07:00–17:00
Record Seattle on Mon 14 Sep 2026 is forecast Busy. 2 cruise ships scheduled, at least 6,718 guests at double occupancy; ships in port 06:00–17:00. Nearest calmer day: Tue 15 Sep (Lively). Ship-by-ship detail for the day, the year at a glance, and what's worth booking ahead: https://avoid-crowds.com/seattle/#d-2026-09-14 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Tue 15 Sep Lively busier than 60% of days here · ⚓3
- Carnival Spirit — guest capacity 2,124 07:00–15:00
- Safari Explorer — guest capacity 36 02:00–?
- Wilderness Explorer — guest capacity 74 02:00–?
Record Seattle on Tue 15 Sep 2026 is forecast Lively. 3 cruise ships scheduled, at least 2,234 guests at double occupancy. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2026-09-15 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Wed 16 Sep Lively busier than 55% of days here
Record Seattle on Wed 16 Sep 2026 is forecast Lively. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2026-09-16 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Thu 17 Sep Busy busier than 68% of days here · ⚓2
- Carnival Miracle — guest capacity 2,124 07:00–15:00
- Queen Elizabeth — guest capacity 2,081
Record Seattle on Thu 17 Sep 2026 is forecast Busy. 2 cruise ships scheduled, at least 4,205 guests at double occupancy. Nearest calmer day: Wed 16 Sep (Lively). Ship-by-ship detail for the day, the year at a glance, and what's worth booking ahead: https://avoid-crowds.com/seattle/#d-2026-09-17 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Fri 18 Sep Busy busier than 70% of days here · ⚓2
- Seven Seas Explorer — guest capacity 754 06:00–17:00
- Voyager Of The Seas — guest capacity 3,416 06:00–16:00
Record Seattle on Fri 18 Sep 2026 is forecast Busy. 2 cruise ships scheduled, at least 4,170 guests at double occupancy; ships in port 06:00–17:00. Nearest calmer day: Wed 16 Sep (Lively). Ship-by-ship detail for the day, the year at a glance, and what's worth booking ahead: https://avoid-crowds.com/seattle/#d-2026-09-18 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Sat 19 Sep Busy busier than 83% of days here · ⚓3
- Norwegian Bliss — guest capacity 4,056 07:00–16:00
- Royal Princess — guest capacity 3,560 07:00–15:00
- ms Eurodam — guest capacity 2,104 07:00–15:00
Record Seattle on Sat 19 Sep 2026 is forecast Busy. 3 cruise ships scheduled, at least 9,720 guests at double occupancy; ships in port 07:00–16:00. Nearest calmer day: Wed 16 Sep (Lively). Ship-by-ship detail for the day, the year at a glance, and what's worth booking ahead: https://avoid-crowds.com/seattle/#d-2026-09-19 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Sun 20 Sep Busy busier than 79% of days here · ⚓2
- Norwegian Encore — guest capacity 3,998 07:00–16:00
- Star Princess — guest capacity 4,320 07:00–15:00
Record Seattle on Sun 20 Sep 2026 is forecast Busy. 2 cruise ships scheduled, at least 8,318 guests at double occupancy; ships in port 07:00–16:00. Nearest calmer day: Tue 22 Sep (Lively). Ship-by-ship detail for the day, the year at a glance, and what's worth booking ahead: https://avoid-crowds.com/seattle/#d-2026-09-20 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Mon 21 Sep Packed busier than 94% of days here · ⚓3
- Anthem of the Seas — guest capacity 4,168 06:00–16:00
- MSC Poesia — guest capacity 2,550 07:00–17:00
- Norwegian Joy — guest capacity 3,804 07:00–16:00
Record Seattle on Mon 21 Sep 2026 is forecast Packed. 3 cruise ships scheduled, at least 10,522 guests at double occupancy; ships in port 06:00–17:00. Nearest calmer day: Sun 20 Sep (Busy). Ship-by-ship detail for the day, the year at a glance, and what's worth booking ahead: https://avoid-crowds.com/seattle/#d-2026-09-21 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Tue 22 Sep Lively busier than 55% of days here
Record Seattle on Tue 22 Sep 2026 is forecast Lively. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2026-09-22 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Wed 23 Sep Lively busier than 62% of days here · ⚓2
- Carnival Spirit — guest capacity 2,124 07:00–16:00
- Safari Quest — guest capacity 16 02:00–?
Record Seattle on Wed 23 Sep 2026 is forecast Lively. 2 cruise ships scheduled, at least 2,140 guests at double occupancy. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2026-09-23 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Thu 24 Sep Lively busier than 62% of days here · ⚓1 · KR public holiday
- Queen Elizabeth — guest capacity 2,081
Record Seattle on Thu 24 Sep 2026 is forecast Lively. 1 cruise ship scheduled, at least 2,081 guests at double occupancy. Why: KR public holiday. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2026-09-24 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Fri 25 Sep Busy busier than 68% of days here · ⚓1 · China public holiday
- Voyager Of The Seas — guest capacity 3,416 06:00–16:00
Record Seattle on Fri 25 Sep 2026 is forecast Busy. 1 cruise ship scheduled, at least 3,416 guests at double occupancy; ships in port 06:00–16:00. Why: China public holiday; KR public holiday. Nearest calmer day: Thu 24 Sep (Lively). Ship-by-ship detail for the day, the year at a glance, and what's worth booking ahead: https://avoid-crowds.com/seattle/#d-2026-09-25 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Sat 26 Sep Busy busier than 77% of days here · ⚓4 · KR public holiday
- Carnival Miracle — guest capacity 2,124 07:00–16:00
- Norwegian Bliss — guest capacity 4,056 07:00–16:00
- Safari Endeavour — guest capacity 84
- ms Eurodam — guest capacity 2,104 07:00–15:00
Record Seattle on Sat 26 Sep 2026 is forecast Busy. 4 cruise ships scheduled, at least 8,368 guests at double occupancy. Why: KR public holiday. Nearest calmer day: Thu 24 Sep (Lively). Ship-by-ship detail for the day, the year at a glance, and what's worth booking ahead: https://avoid-crowds.com/seattle/#d-2026-09-26 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Sun 27 Sep Busy busier than 69% of days here · ⚓1
- Norwegian Encore — guest capacity 3,998 07:00–16:00
Record Seattle on Sun 27 Sep 2026 is forecast Busy. 1 cruise ship scheduled, at least 3,998 guests at double occupancy; ships in port 07:00–16:00. Nearest calmer day: Tue 29 Sep (Lively). Ship-by-ship detail for the day, the year at a glance, and what's worth booking ahead: https://avoid-crowds.com/seattle/#d-2026-09-27 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Mon 28 Sep Packed busier than 97% of days here · ⚓2
- Anthem of the Seas — guest capacity 4,168 06:00–02:00
- MSC Poesia — guest capacity 2,550 07:00–18:00
Record Seattle on Mon 28 Sep 2026 is forecast Packed. 2 cruise ships scheduled, at least 6,718 guests at double occupancy; ships in port 06:00–18:00. Nearest calmer day: Sun 27 Sep (Busy). Ship-by-ship detail for the day, the year at a glance, and what's worth booking ahead: https://avoid-crowds.com/seattle/#d-2026-09-28 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Tue 29 Sep Lively busier than 55% of days here
Record Seattle on Tue 29 Sep 2026 is forecast Lively. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2026-09-29 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Wed 30 Sep Packed busier than 99% of days here · ⚓3 · Canada public holiday
- Anthem of the Seas — guest capacity 4,168 08:00–18:00
- Norwegian Joy — guest capacity 3,804 07:00–02:00
- Seven Seas Explorer — guest capacity 754 06:00–16:00
Record Seattle on Wed 30 Sep 2026 is forecast Packed. 3 cruise ships scheduled, at least 8,726 guests at double occupancy; ships in port 06:00–18:00. Why: Canada public holiday. Nearest calmer day: Tue 29 Sep (Lively). Ship-by-ship detail for the day, the year at a glance, and what's worth booking ahead: https://avoid-crowds.com/seattle/#d-2026-09-30 (Avoid-Crowds, as of 14 Sep 2026; recomputed nightly.)
Can't move the dates? How to avoid the worst crowds
- The heaviest port day is Mon 21 Sep — 3 ships in at once. See the marquee sights on a lighter day, or be there for opening time.
- Need flexibility? The 22nd–24th is the month's calmest stretch — the easiest window to move around in.
- On the busy days, the walk-up queues for the big sights are the biggest time-sink — a timed-entry ticket skips them, which is where a busy month is won or lost.
Travelling on a busy day?
Timed-entry and skip-the-line tickets turn queue time into sightseeing time — sort them before you fly.
September weather in Seattle
Comfortably warm — around 21°C / 70°F, easy shirtsleeve weather, with rain on about 11 days, so keep a layer handy.
Book beds and the big-ticket sights well ahead, and start your days by eight — in a month this full, the early hours are the only uncrowded ones.
More about Seattle in September
Based on: United States' public holidays · the official airport-arrivals pattern (BTS T-100, measured 2023–2025; airport-arrivals proxy for visitor volume) · five years of weather records (2019–2023) · confirmed event dates · the published cruise schedule
Every figure is recomputed nightly from real cruise schedules, public and school holidays, and long-run climate normals. Gaps are shown, not filled.
