Carrier route record
WNSEA→OAK
Southwest Airlines · Seattle to Oakland
- Flights
- 1,088
- 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 SEA to OAK sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.3%. The late ones land roughly 50 minutes behind schedule. That rests on 1,088 flights, with a median arrival 1 minute late.
The national on-time rate over the same period is 77.3%, so Southwest on SEA to OAK runs 8 points behind the country as a whole. Across a thousand flights that is about 75 extra late arrivals.
Key figures
On time
69.8%
Arrivals under 15 minutes late, of 1,085 completed flights
Avg delay
52 min
Across delayed arrivals only, not all flights
Cancelled
0.28%
National rate is 1.89%
Whole route
73.7%
Every carrier on SEA to OAK, 1,914 flights
These figures cover 1,088 flights between September 2025 and August 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Carrier by carrier
Southwest against every carrier on SEA to OAK
Southwest flew 1,088 of the 1,914 flights on SEA to OAK, most of the route. Its 69.8% on time is 4 points worse than the route as a whole, which runs 73.7%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from SkyWest at 92.3% to Southwest at 69.8%. 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 | 41 | 92.3% | 72 min | 4.88% | A− |
| Alaska Airlines | 785 | 78.3% | 49 min | 1.27% | B |
| Southwest Airlines (this page) | 1,088 | 69.8% | 52 min | 0.28% | C+ |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 51 points, against half a point between the best and worst carrier.
- 5am–8am192 flights97.4%
- 8am–11am255 flights82.0%
- 11am–2pm140 flights70.7%
- 2pm–5pm108 flights46.3%
- 5pm–8pm242 flights57.4%
- 8pm–5am151 flights50.0%
Scale runs 40% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 97.4% of the time, against 46.3% for the afternoon window. That is 51 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 255 flights scheduled in it.
Across the year
Southwest on SEA to OAK through the year
August is the worst month at 48.6% on time, 34 points below January, the best at 82.6%. 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, Wednesday is the strongest day at 83.3% on time and Sunday the weakest at 57.7%, a spread of 26 points.
Arrival by arrival
How late Southwest on SEA to OAK runs when it is late
The 328 late arrivals split 126 under half an hour, 119 between 30 and 60 minutes, and 83 an hour or more.
- 15+ min early167 flights15.4%
- Within 15 min590 flights54.4%
- 15–29 min late126 flights11.6%
- 30–59 min late119 flights11.0%
- 1–2 hours late66 flights6.1%
- 2+ hours late17 flights1.6%
Scale runs 0% to 100%.
Share of 1,085 completed flights by arrival against schedule.
103 of 410 late departures made up the time and arrived on time, 25% of them. Only 21 left on time and still arrived late.
The worst days
Worst days for Southwest on SEA to OAK
The latest arrival of the period was on 3 April 2026, 10 hours 45 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). On four of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 3 April 2026 | 10 hours 45 minutes | Carrier |
| 27 July 2026 | 5 hours 41 minutes | Late-arriving aircraft |
| 17 February 2026 | 4 hours 36 minutes | Late-arriving aircraft |
| 9 August 2026 | 4 hours 26 minutes | Late-arriving aircraft |
| 11 June 2026 | 4 hours 13 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 60% of the 17,000 delay minutes carriers reported here, and the remaining four split what is left.
- 60%Late-arriving aircraft
- 32%Carrier
- 6%National Airspace System
- 1%Extreme weather
- 0%Security
60% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 17,000 reported delay minutes here, that single category outweighs weather by 60 to one. The split is drawn from 17,080 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 97.4% 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
7.6% 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 73.8% on time across 1,090 flights, 4 points above 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. 1,088 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 SEA to OAK
Put together: treat all of this as provisional. 1,088 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 69.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,085 completed flights over 12 months sit behind that.
Related
Where to go next
- SEA to OAK, every carrier
- Southwest on OAK to SEA, the return leg
- Alaska Airlines on SEA to OAK78.3%
- Southwest Airlines network-wide record
- Seattle-Tacoma International (SEA) delay statistics
- Oakland International (OAK) 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.