Flight number record

DL 2635

Delta Air Lines · Seattle to San Francisco

Route: SEA → SFO
Departs: 21:20
Flights: 340
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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 B+. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.6%. The late ones land roughly 50 minutes behind schedule. That rests on 340 flights, with a median arrival 2 minutes early.

On time

75.1%

Arrivals under 15 minutes late, of 337 completed flights

Avg delay

52 min

Across delayed arrivals only, not all flights

Cancelled

0.88%

National rate is 1.81%

1 hour+ late

5.3%

National rate is 8.1%

These figures cover 340 flights between July 2025 and June 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.

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 95 of 340 flights, with 21:45 (84 flights) and 22:05 (39 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 21:2095 flights27.9%
Departs 21:4584 flights24.7%
Departs 22:0539 flights11.5%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

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 70.5%, and DL 2635 runs 5 points better at 75.1%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

Against the route

DL 2635 next to SEA to SFO

Every carrier on SEA to SFO combined arrived on time 65.6% of the time across 6,764 flights, so DL 2635 is 10 points ahead of it. Delta flew 923 flights on the same city pair under all its flight numbers, including this one, and those ran 67.3% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 7 points.

DL 2635 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 2635thin sample	340	75.1%	52 min	0.88%	B+
All Delta Air Lines on SEA–SFO	923	67.3%	56 min	1.63%	C
All carriers on SEA–SFO	6,764	65.6%	59 min	1.20%	C
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 2635 quarter by quarter

Quarter by quarter DL 2635 held fairly steady: 81.2% in Jul–Sep 2025, 71.8% in Oct–Dec 2025, 74.7% in Jan–Mar 2026 and 72.5% in Apr–Jun 2026. A spread of 9 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202585 flights81.2%
Oct–Dec 202578 flights71.8%
Jan–Mar 202686 flights74.7%
Apr–Jun 202691 flights72.5%

Scale runs 65% to 85%. Rows with fewer than 30 flights show a dash.

By weekday, DL 2635 did best on Saturday at 87.2% on time and worst on Sunday at 62.5%. Each day rests on about 49 flights, so a gap of 25 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 2635 runs late

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 4,380 reported delay minutes.

Carrier
36%
National Airspace System
34%
Late-arriving aircraft
28%
Extreme weather
3%

The largest share of delay minutes, 36%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 1,557 of the 4,380 delay minutes reported here. The split is drawn from 4,380 delay minutes reported on DL 2635.

Cancellations are rare at 0.88%, below the national 1.81% 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 routes

What a delay on this flight costs

5.3% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says 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 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

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 75.1% on time with 0.88% cancelled over 340 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures