Carrier route record
WNOAK→SEA
Southwest Airlines · Oakland to Seattle
- Flights
- 1,090
- Period
- September 2025 to August 2026
- Share of route
- 57%
- Carriers
- 3
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on OAK to SEA sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.3%. The late ones land roughly 50 minutes behind schedule. That rests on 1,090 flights, with a median arrival 2 minutes early.
The US average over the same twelve months is 77.3%, so there is little to separate Southwest on OAK to SEA from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
73.8%
Arrivals under 15 minutes late, of 1,087 completed flights
Avg delay
48 min
Across delayed arrivals only, not all flights
Cancelled
0.28%
National rate is 1.89%
Whole route
77.3%
Every carrier on OAK to SEA, 1,896 flights
These figures cover 1,090 flights between September 2025 and August 2026. The median arrival is 2 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
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Carrier by carrier
Southwest against every carrier on OAK to SEA
Southwest flew 1,090 of the 1,896 flights on OAK to SEA, most of the route. Its 73.8% on time is 4 points worse than the route as a whole, which runs 77.3%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from SkyWest at 94.7% to Southwest at 73.8%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 21 | 94.7% | 22 min | 9.52% | A− |
| Alaska Airlines | 785 | 81.9% | 45 min | 1.53% | B |
| Southwest Airlines (this page) | 1,090 | 73.8% | 48 min | 0.28% | C+ |
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Departure window
When Southwest runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 35 points, against half a point between the best and worst carrier.
- 5am–8am241 flights95.4%
- 8am–11am161 flights70.8%
- 11am–2pm171 flights81.2%
- 2pm–5pm96 flights67.4%
- 5pm–8pm220 flights61.4%
- 8pm–5am201 flights60.7%
Scale runs 50% to 100%.
The 8pm–5am window is where this operation falls apart: 60.7% on time, against 95.4% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5am–8am window is the busiest, with 241 flights scheduled in it.
Across the year
Southwest on OAK to SEA through the year
June is the worst month at 51.9% on time, 39 points below January, the best at 90.7%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. September was the busiest month here, with 120 flights.
Across the week, Saturday is the strongest day at 87.2% on time and Sunday the weakest at 68.9%, a spread of 18 points.
Arrival by arrival
How late Southwest on OAK to SEA runs when it is late
The 285 late arrivals split 119 under half an hour, 98 between 30 and 60 minutes, and 68 an hour or more.
- 15+ min early253 flights23.3%
- Within 15 min549 flights50.5%
- 15–29 min late119 flights10.9%
- 30–59 min late98 flights9.0%
- 1–2 hours late54 flights5.0%
- 2+ hours late14 flights1.3%
Scale runs 0% to 100%.
Share of 1,087 completed flights by arrival against schedule.
82 of 319 late departures made up the time and arrived on time, 26% of them. 48 flights left on time and still arrived late.
The worst days
Worst days for Southwest on OAK to SEA
The latest arrival of the period was on 18 September 2025, 4 hours 21 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. On three of the five worst days the largest share was filed as carrier-caused (crew, maintenance, fuelling, baggage).
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 18 September 2025 | 4 hours 21 minutes | Late-arriving aircraft |
| 29 July 2026 | 3 hours 34 minutes | Carrier |
| 29 April 2026 | 3 hours 16 minutes | Carrier |
| 7 September 2025 | 2 hours 51 minutes | Late-arriving aircraft |
| 14 November 2025 | 2 hours 35 minutes | Carrier |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 50% of the 14,000 delay minutes carriers reported here, and the remaining four split what is left.
- 50%Late-arriving aircraft
- 30%Carrier
- 20%National Airspace System
- 0%Extreme weather
50% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 14,000 reported delay minutes here, that single category outweighs weather by 50 to one. The split is drawn from 13,552 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 95.4% on time here.
Cancellations are rare at 0.28%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here costs
6.3% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last roughly 50 minutes, which a normal layover absorbs.
The 672 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg is a different operation and performs like one: it runs 69.8% on time across 1,088 flights, 4 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.
One caution: this is a thin sample. 1,090 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking Southwest on OAK to SEA
Put together: treat all of this as provisional. 1,090 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 73.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,087 completed flights over 12 months sit behind that.
Related
Where to go next
- OAK to SEA, every carrier
- Southwest on SEA to OAK, the return leg
- Alaska Airlines on OAK to SEA81.9%
- Southwest Airlines network-wide record
- Oakland International (OAK) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.