Flight number record
DL 2635
Delta Air Lines · Seattle to San Francisco
- Route
- SEA → SFO
- Departs
- 21:20
- Flights
- 340
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 2635, check with Delta Air Lines.
DL 2635 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 about an hour behind schedule. That rests on 340 flights, with a median arrival right on schedule.
The national on-time rate over the same period is 77.3%, so DL 2635 runs 8 points behind the country as a whole. Across a thousand flights that is about 77 extra late arrivals.
Key figures
On time
69.6%
Arrivals under 15 minutes late, of 336 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
1.18%
National rate is 1.89%
1 hour+ late
7.1%
National rate is 8.3%
These figures cover 340 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.
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Schedule
When DL 2635 flies
DL 2635 flies SEA to SFO without a single fixed slot. Its most common scheduled departure was 21:20, used on 90 of 340 flights, with 21:45 (90 flights) and 20:10 (38 flights) next.
- Departs 21:2090 flights26.5%
- Departs 21:4590 flights26.5%
- Departs 20:1038 flights11.2%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 21:20 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.1%, and DL 2635 runs level with that at 69.6%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
DL 2635 next to SEA to SFO
Every carrier on SEA to SFO combined arrived on time 59.8% of the time across 6,817 flights, so DL 2635 is 10 points ahead of it. Delta flew 985 flights on the same city pair under all its flight numbers, including this one, and those ran 60.5% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 12 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 2635thin sample | 340 | 69.6% | 58 min | 1.18% | C |
| All Delta Air Lines on SEA–SFO | 985 | 60.5% | 54 min | 1.73% | D |
| All carriers on SEA–SFO | 6,817 | 59.8% | 57 min | 1.11% | D |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 2635 quarter by quarter
DL 2635 did not run the same all year. Its best quarter was Jan–Mar 2026 at 74.7% on time and its weakest Jul–Sep 2026 at 47.5%, a swing of 27 points on roughly 85 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202523 flights—
- Oct–Dec 202578 flights71.8%
- Jan–Mar 202686 flights74.7%
- Apr–Jun 202691 flights72.5%
- Jul–Sep 202662 flights47.5%
Scale runs 40% to 80%. Rows with fewer than 30 flights show a dash.
By weekday, DL 2635 did best on Saturday at 89.4% on time and worst on Sunday at 58.3%. Each day rests on about 49 flights, so a gap of 31 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 2635 runs when it is late
The 102 late arrivals split 37 under half an hour, 41 between 30 and 60 minutes, and 24 an hour or more.
- 15+ min early68 flights20.2%
- Within 15 min166 flights49.4%
- 15–29 min late37 flights11.0%
- 30–59 min late41 flights12.2%
- 1–2 hours late17 flights5.1%
- 2+ hours late7 flights2.1%
Scale runs 0% to 100%.
Share of 336 completed flights by arrival against schedule.
18 of 99 late departures made up the time and arrived on time, 18% of them. In the other direction, 21 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SFO.
The worst days
Worst days for DL 2635
The latest arrival of the period was on 22 July 2026, 10 hours 49 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 22 July 2026 | 10 hours 49 minutes | Carrier |
| 23 January 2026 | 9 hours 44 minutes | Carrier |
| 24 August 2026 | 3 hours 1 minute | Late-arriving aircraft |
| 27 October 2025 | 2 hours 49 minutes | Carrier |
| 12 November 2025 | 2 hours 12 minutes | National Airspace System |
Delay causes
Why DL 2635 runs late
Carrier accounts for 43% of the 5,950 delay minutes carriers reported here, and the remaining four split what is left.
- 43%Carrier
- 29%National Airspace System
- 26%Late-arriving aircraft
- 1%Extreme weather
The largest share of delay minutes, 43%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,561 of the 5,950 delay minutes reported here. The split is drawn from 5,950 delay minutes reported on DL 2635.
Cancellations sit at 1.18% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
7.1% 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 about an hour, which a normal layover absorbs.
The 679 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 same number turns up on one other city pair in the data, including MCO to SEA (12), but none flew often enough under DL 2635 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to SEA to SFO only.
One caution: this is a thin sample. 340 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 DL 2635
For a booking, read DL 2635 as 69.6% on time with 1.18% cancelled over 340 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- SEA to SFO, every carrier and departure
- SFO to SEA, the return direction
- United Airlines 737 on the same route53.9%
- Delta Air Lines 1412 on the same route60.1%
- SkyWest Airlines 3707 on the same route68.5%
- Alaska Airlines 655 on the same route67.2%
- Alaska Airlines 725 on the same route50.5%
- SkyWest Airlines 3991 on the same route59.9%
- Seattle-Tacoma International (SEA) delay statistics
- San Francisco International (SFO) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- Worst months to fly in the US, ranked by the data
A flight number here means Delta Air Lines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
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.