Updated 29 Oct 2026 · recomputed nightly
Is September 2027 a good month to visit Seattle?
Busy — the typical September day in Seattle is busier than 74% 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 (6).
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 12 of 30 days.
No. The typical September day in Seattle is Busy, and 20 of the 30 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 Canada add to it. Cruise ships call on 24 of the 30 days, 3 at once on Monday 27 September. Costco Wholesale 2027 Supplier Day & Scholarship Breakfast falls on 9–10 September. Late September is the month's quietest stretch in Seattle — the typical day at 66%, against 80% in early 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.
In short, a hard sell — heavy crowds without the best of the weather.
Among the 12 months we forecast for Seattle, September ranks 6th for crowd pressure. Its heaviest day is Mon 27 Sep, busier than 100% of the year; its lightest is Wed 1 Sep at 54%.
⚠︎ Weekends run heavy — the 4th, 5th, 11th, 12th, 18th, 19th, 25th and 26th 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 6th, 10th, 17th and 27th, and 16 more. Away from those, most days sit Lively. The calmest stretch is the 14th–16th.
Cruise ships are in port on 24 of 30 days; the heaviest is Mon 27 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 54% of the year and its heaviest at 100%, so where you land inside it matters. All four Fridays run Busy or Packed. Daylight runs about 12 hours.
Either side of it, August is busier still and October is far calmer.
Weekends run heavy — the 4th, 5th, 11th, 12th, 18th, 19th, 25th and 26th all sit Busy or Packed. If your dates can flex, a midweek arrival is the single easiest win.
Wed 01 Sep Lively busier than 54% of days here
Record Seattle on Wed 1 Sep 2027 is forecast Lively. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2027-09-01 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Thu 02 Sep Busy busier than 73% of days here · ⚓4
- Brilliant Lady — guest capacity 2,770 07:00–17:00
- Carnival Spirit — guest capacity 2,124 07:00–15:00
- MS Fridtjof Nansen — guest capacity 530
- Oceania Riviera — guest capacity 1,258 08:00–17:00
Record Seattle on Thu 2 Sep 2027 is forecast Busy. 4 cruise ships scheduled, at least 6,682 guests at double occupancy. Nearest calmer day: Wed 1 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-2027-09-02 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Fri 03 Sep Busy busier than 77% of days here · ⚓3
- Celebrity Edge — guest capacity 2,918 06:00–16:00
- MS Fridtjof Nansen — guest capacity 530
- Voyager Of The Seas — guest capacity 3,416 06:00–16:00
Record Seattle on Fri 3 Sep 2027 is forecast Busy. 3 cruise ships scheduled, at least 6,864 guests at double occupancy. Nearest calmer day: Wed 1 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-2027-09-03 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Sat 04 Sep Packed busier than 88% of days here · ⚓4
- MS Fridtjof Nansen — guest capacity 530
- Norwegian Bliss — guest capacity 4,056 06:00–15:00
- Royal Princess — guest capacity 3,560 07:00–15:00
- ms Eurodam — guest capacity 2,104 07:00–15:00
Record Seattle on Sat 4 Sep 2027 is forecast Packed. 4 cruise ships scheduled, at least 10,250 guests at double occupancy. Nearest calmer day: Fri 3 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-2027-09-04 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Sun 05 Sep Busy busier than 84% of days here · ⚓3
- Norwegian Encore — guest capacity 3,998 07:00–15:00
- Star Princess — guest capacity 4,320 07:00–15:00
- ms Noordam — guest capacity 1,972 07:00–15:00
Record Seattle on Sun 5 Sep 2027 is forecast Busy. 3 cruise ships scheduled, at least 10,290 guests at double occupancy; ships in port 07:00–15:00. Nearest calmer day: Tue 7 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-2027-09-05 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Mon 06 Sep Packed busier than 99% of days here · ⚓2 · United States public holiday · Labor Day
Event on this day
6 Sep 2027The last long weekend of the American summer. It is the hardest weekend of the year in the centre of Seattle, and the week after it is noticeably quieter.
- MSC Poesia — guest capacity 2,550 07:00–16:00
- Quantum Of The Seas — guest capacity 4,162 06:00–16:00
Record Seattle on Mon 6 Sep 2027 is forecast Packed. 2 cruise ships scheduled, at least 6,712 guests at double occupancy; ships in port 06:00–16:00. Why: United States public holiday; Canada public holiday; Labor Day. Nearest calmer day: Sun 5 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-2027-09-06 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Tue 07 Sep Lively busier than 59% of days here · ⚓1
- Carnival Legend — guest capacity 2,124 07:00–15:00
Record Seattle on Tue 7 Sep 2027 is forecast Lively. 1 cruise ship scheduled, at least 2,124 guests at double occupancy; ships in port 07:00–15:00. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2027-09-07 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Wed 08 Sep Busy busier than 67% of days here · ⚓1
- Norwegian Joy — guest capacity 3,804 06:00–15:00
Record Seattle on Wed 8 Sep 2027 is forecast Busy. 1 cruise ship scheduled, at least 3,804 guests at double occupancy; ships in port 06:00–15:00. Nearest calmer day: Tue 7 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-2027-09-08 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Thu 09 Sep Packed busier than 89% of days here · ⚓1 · Costco Wholesale 2027 Supplier Day & Scholarship Breakfast
- Carnival Spirit — guest capacity 2,124 07:00–15:00
Record Seattle on Thu 9 Sep 2027 is forecast Packed. 1 cruise ship scheduled, at least 2,124 guests at double occupancy; ships in port 07:00–15:00. Why: Costco Wholesale 2027 Supplier Day & Scholarship Breakfast. Nearest calmer day: Wed 8 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-2027-09-09 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Fri 10 Sep Packed busier than 99% of days here · ⚓2 · Costco Wholesale 2027 Supplier Day & Scholarship Breakfast
- Celebrity Edge — guest capacity 2,918 06:00–16:00
- Voyager Of The Seas — guest capacity 3,416 06:00–16:00
Record Seattle on Fri 10 Sep 2027 is forecast Packed. 2 cruise ships scheduled, at least 6,334 guests at double occupancy; ships in port 06:00–16:00. Why: Costco Wholesale 2027 Supplier Day & Scholarship Breakfast. Nearest calmer day: Sat 11 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-2027-09-10 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Sat 11 Sep Busy busier than 84% of days here · ⚓3
- Norwegian Bliss — guest capacity 4,056 06:00–15:00
- Royal Princess — guest capacity 3,560 07:00–15:00
- ms Eurodam — guest capacity 2,104 07:00–15:00
Record Seattle on Sat 11 Sep 2027 is forecast Busy. 3 cruise ships scheduled, at least 9,720 guests at double occupancy; ships in port 06:00–15:00. Nearest calmer day: Tue 14 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-2027-09-11 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Sun 12 Sep Packed busier than 88% of days here · ⚓3
- Norwegian Encore — guest capacity 3,998 07:00–15:00
- Star Princess — guest capacity 4,320 07:00–15:00
- ms Noordam — guest capacity 1,972 07:00–17:00
Record Seattle on Sun 12 Sep 2027 is forecast Packed. 3 cruise ships scheduled, at least 10,290 guests at double occupancy; ships in port 07:00–17:00. Nearest calmer day: Sat 11 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-2027-09-12 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Mon 13 Sep Busy busier than 75% of days here · ⚓2
- MSC Poesia — guest capacity 2,550 07:00–16:00
- Quantum Of The Seas — guest capacity 4,162 06:00–16:00
Record Seattle on Mon 13 Sep 2027 is forecast Busy. 2 cruise ships scheduled, at least 6,712 guests at double occupancy; ships in port 06:00–16:00. Nearest calmer day: Tue 14 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-2027-09-13 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Tue 14 Sep Lively busier than 61% of days here · ⚓3 · KR public holiday
- Carnival Legend — 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 14 Sep 2027 is forecast Lively. 3 cruise ships scheduled, at least 2,234 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-2027-09-14 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Wed 15 Sep Lively busier than 55% of days here · China public holiday
Record Seattle on Wed 15 Sep 2027 is forecast Lively. Why: China public holiday; KR public holiday. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2027-09-15 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Thu 16 Sep Lively busier than 62% of days here · ⚓1 · KR public holiday
- Carnival Spirit — guest capacity 2,124 07:00–16:00
Record Seattle on Thu 16 Sep 2027 is forecast Lively. 1 cruise ship scheduled, at least 2,124 guests at double occupancy; ships in port 07:00–16:00. Why: KR public holiday. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2027-09-16 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Fri 17 Sep Packed busier than 91% of days here · ⚓3
- Celebrity Edge — guest capacity 2,918 06:00–16:00
- Norwegian Joy — guest capacity 3,804 06:00–15:00
- Voyager Of The Seas — guest capacity 3,416 06:00–16:00
Record Seattle on Fri 17 Sep 2027 is forecast Packed. 3 cruise ships scheduled, at least 10,138 guests at double occupancy; ships in port 06:00–16:00. Nearest calmer day: Thu 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-2027-09-17 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Sat 18 Sep Busy busier than 72% of days here · ⚓2
- Norwegian Bliss — guest capacity 4,056 06:00–15:00
- ms Eurodam — guest capacity 2,104 07:00–15:00
Record Seattle on Sat 18 Sep 2027 is forecast Busy. 2 cruise ships scheduled, at least 6,160 guests at double occupancy; ships in port 06:00–15:00. Nearest calmer day: Thu 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-2027-09-18 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Sun 19 Sep Packed busier than 88% of days here · ⚓3
- Norwegian Encore — guest capacity 3,998 07:00–15:00
- Star Princess — guest capacity 4,320 07:00–15:00
- ms Westerdam — guest capacity 1,968 07:00–17:00
Record Seattle on Sun 19 Sep 2027 is forecast Packed. 3 cruise ships scheduled, at least 10,286 guests at double occupancy; ships in port 07:00–17:00. Nearest calmer day: Sat 18 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-2027-09-19 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Mon 20 Sep Busy busier than 75% of days here · ⚓2
- MSC Poesia — guest capacity 2,550 07:00–16:00
- Quantum Of The Seas — guest capacity 4,162 06:00–16:00
Record Seattle on Mon 20 Sep 2027 is forecast Busy. 2 cruise ships scheduled, at least 6,712 guests at double occupancy; ships in port 06:00–16:00. Nearest calmer day: Tue 21 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-2027-09-20 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Tue 21 Sep Lively busier than 62% of days here · ⚓1
- Carnival Legend — guest capacity 2,124 07:00–16:00
Record Seattle on Tue 21 Sep 2027 is forecast Lively. 1 cruise ship scheduled, at least 2,124 guests at double occupancy; ships in port 07:00–16:00. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2027-09-21 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Wed 22 Sep Busy busier than 69% of days here · ⚓1
- Ruby Princess — guest capacity 3,060 07:00–19:00
Record Seattle on Wed 22 Sep 2027 is forecast Busy. 1 cruise ship scheduled, at least 3,060 guests at double occupancy; ships in port 07:00–19:00. Nearest calmer day: Tue 21 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-2027-09-22 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Thu 23 Sep Lively busier than 54% of days here
Record Seattle on Thu 23 Sep 2027 is forecast Lively. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2027-09-23 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Fri 24 Sep Busy busier than 74% of days here · ⚓2
- Celebrity Edge — guest capacity 2,918 06:00–16:00
- Voyager Of The Seas — guest capacity 3,416 06:00–16:00
Record Seattle on Fri 24 Sep 2027 is forecast Busy. 2 cruise ships scheduled, at least 6,334 guests at double occupancy; ships in port 06:00–16:00. Nearest calmer day: Thu 23 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-2027-09-24 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Sat 25 Sep Busy busier than 78% of days here · ⚓3
- Carnival Spirit — guest capacity 2,124 07:00–16:00
- Norwegian Bliss — guest capacity 4,056 06:00–15:00
- ms Eurodam — guest capacity 2,104 07:00–15:00
Record Seattle on Sat 25 Sep 2027 is forecast Busy. 3 cruise ships scheduled, at least 8,284 guests at double occupancy; ships in port 06:00–16:00. Nearest calmer day: Thu 23 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-2027-09-25 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Sun 26 Sep Busy busier than 76% of days here · ⚓2
- Norwegian Encore — guest capacity 3,998 07:00–15:00
- Star Princess — guest capacity 4,320 07:00–15:00
Record Seattle on Sun 26 Sep 2027 is forecast Busy. 2 cruise ships scheduled, at least 8,318 guests at double occupancy; ships in port 07:00–15:00. Nearest calmer day: Tue 28 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-2027-09-26 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Mon 27 Sep Packed the busiest day in our forecast · ⚓3
- MSC Poesia — guest capacity 2,550 07:00–18:00
- Norwegian Joy — guest capacity 3,804 06:00–02:00
- Quantum Of The Seas — guest capacity 4,162 06:00–16:00
Record Seattle on Mon 27 Sep 2027 is forecast Packed, the busiest day of its forecast year. 3 cruise ships scheduled, at least 10,516 guests at double occupancy; ships in port 06:00–18:00. Nearest calmer day: Sun 26 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-2027-09-27 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Tue 28 Sep Lively busier than 54% of days here
Record Seattle on Tue 28 Sep 2027 is forecast Lively. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2027-09-28 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Wed 29 Sep Lively busier than 54% of days here · ⚓1
- Safari Quest — guest capacity 16 02:00–?
Record Seattle on Wed 29 Sep 2027 is forecast Lively. 1 cruise ship scheduled, at least 16 guests at double occupancy. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2027-09-29 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Thu 30 Sep Lively busier than 55% of days here · ⚓1 · Canada public holiday
- Wilderness Legacy — guest capacity 88 02:00–?
Record Seattle on Thu 30 Sep 2027 is forecast Lively. Why: Canada public holiday. 1 cruise ship scheduled, at least 88 guests at double occupancy. The day in full, the year at a glance, and how this day compares: https://avoid-crowds.com/seattle/#d-2027-09-30 (Avoid-Crowds, as of 29 Oct 2026; recomputed nightly.)
Which week of September is quietest in Seattle?
Late September is the month's quietest stretch in Seattle — the typical day at 66%, against 80% in early September.
Can't move the dates? How to avoid the worst crowds
- The heaviest port day is Mon 27 Sep — 3 ships in at once. See the marquee sights on a lighter day, or be there for opening time.
- Need flexibility? The 14th–16th 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.
