Airport month record

SEAAPR

Seattle-Tacoma International in April 2026

Departures: 12,864
Month: April 2026
National, same month: 79.8%
Carriers: 8

Historical statistics for April 2026, not live status or a forecast for this year’s April. For today’s conditions at SEA, see live FAA status.

SEA in April earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 6 points better than the national rate of 79.8%. When something does go wrong the average delay runs about an hour. That rests on 12,864 flights, of which SkyWest Airlines flew 2,147 at 89.1% on time.

SkyWest Airlines is the most reliable of the six carriers covered here at 89.1% on time across 2,147 flights.

On time

85.6%

Arrivals under 15 minutes late, of 12,818 completed departures

Avg delay

56 min

Across delayed arrivals only, not all flights

Cancelled

0.17%

Nationally in April: 0.90%

Whole year

79.4%

SEA across all twelve months

These figures cover 12,864 departures from Seattle-Tacoma International in April 2026. On time means an arrival less than 15 minutes after the scheduled gate time, the DOT's threshold, and the national comparison uses every US departure in the same month rather than the whole year.

Against the year

April next to SEA's other months

Against SEA's own year, April ran 6 points better than the twelve-month rate of 79.4%, which makes it the best of the twelve months in the data. Cancellations were unusually low for SEA in April, at 0.17% against 0.99% across the year. Either side of it, March ran 80.2% on time and May 82.2%, so a trip moved by a few weeks would have landed in a worse stretch.

SEA month by month
Month	Flights	On time	Avg delay	Cancelled	Grade
July 2025	16,577	69.2%	57 min	1.38%	C
August 2025	15,970	73.6%	51 min	0.66%	C+
September 2025	14,552	82.9%	50 min	0.29%	B+
October 2025	13,859	82.9%	58 min	1.16%	B
November 2025	12,616	81.9%	58 min	1.69%	B
December 2025	13,023	74.0%	59 min	1.02%	C
January 2026	11,927	81.6%	60 min	1.91%	B
February 2026	11,000	84.4%	56 min	0.78%	B+
March 2026	12,830	80.2%	64 min	2.23%	B
April 2026 (this page)	12,864	85.6%	56 min	0.17%	A+
May 2026	14,564	82.2%	52 min	0.41%	B+
June 2026	15,402	78.1%	57 min	0.48%	B+

Departure window

The best time of day to leave SEA in April

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 13,000 flights.

5am–8am1,562 flights89.2%
8am–11am2,575 flights87.7%
11am–2pm2,522 flights84.8%
2pm–5pm1,726 flights86.1%
5pm–8pm1,852 flights83.9%
8pm–5am2,627 flights82.8%

Scale runs 75% to 95%. Rows with fewer than 30 flights show a dash.

The early departures do better, though not dramatically: 89.2% on time for the 5am–8am window against 82.8% for 8pm–5am. Worth taking if the schedule allows, not worth an extra connection. The 8pm–5am window is the busiest, with 2,627 flights scheduled in it.

Across the week, Saturday is the strongest day at 90.5% on time and Thursday the weakest at 81.5%. 9 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at SEA in April

The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 89.1% of the time; Southwest Airlines manages 73.6%. Sample sizes sit next to every figure, because a two-point gap across 588 flights means less than a ten-point one.

Carriers at SEA in April 2026
Airline	Flights	On time	Avg delay	Cancelled	Grade
Alaska Airlines	6,097	86.6%	45 min	0.08%	A+
Delta Air Lines	2,662	85.1%	67 min	0.26%	A+
SkyWest Airlines	2,147	89.1%	56 min	0.05%	A+
United Airlines	628	78.1%	59 min	0.16%	B+
Southwest Airlines	588	73.6%	46 min	0.17%	C+
American Airlines	564	83.8%	117 min	0.89%	B+
Frontier Airlinesthin sample	99	74.2%	60 min	2.02%	C
Envoy Airthin sample	79	96.2%	19 min	0.00%	A+

The spread between SkyWest and Southwest is 16 points, wide enough that it should decide the booking. On a hundred trips that is 16 more arrivals inside the on-time window.

Route by route

Busiest routes out of SEA in April

Routes from SEA in April 2026
Route	Flights	On time	Avg delay	Cancelled	Grade
SEA to PHX · Phoenix	665	85.8%	54 min	0.15%	A+
SEA to LAX · Los Angeles	611	89.5%	59 min	0.49%	A+
SEA to SFO · San Francisco	495	48.5%	49 min	0.00%	F+
SEA to LAS · Las Vegas	476	84.4%	48 min	0.21%	B+
SEA to DEN · Denver	470	87.6%	44 min	0.21%	A+
SEA to ORD · Chicago	465	79.7%	86 min	1.08%	B
SEA to ANC · Anchorage	452	84.1%	42 min	0.00%	B+
SEA to DFW · Dallas-Fort Worth	414	84.8%	118 min	0.72%	B+
SEA to SAN · San Diego	409	88.0%	42 min	0.00%	A+
SEA to GEG · Spokane	386	86.0%	47 min	0.00%	A+
SEA to PDX · Portland	374	90.6%	65 min	0.27%	A+
SEA to SMF · Sacramento	369	87.5%	48 min	0.00%	A+
SEA to BOI · Boisethin sample	355	89.3%	46 min	0.00%	A+
SEA to SLC · Salt Lake Citythin sample	314	92.4%	51 min	0.00%	A+
SEA to SJC · San Josethin sample	305	89.5%	32 min	0.00%	A+
SEA to SNA · Santa Anathin sample	301	91.0%	68 min	0.00%	A+
SEA to ATL · Atlantathin sample	251	85.5%	48 min	0.80%	A+
SEA to HNL · Honoluluthin sample	239	76.5%	122 min	0.42%	B+
SEA to JFK · New Yorkthin sample	225	83.9%	59 min	0.00%	B+
SEA to PSP · Palm Springsthin sample	216	91.2%	43 min	0.00%	A+
SEA to ONT · Ontariothin sample	200	89.5%	54 min	0.00%	A+
SEA to MSP · Minneapolisthin sample	198	90.8%	54 min	0.51%	A+
SEA to EWR · Newarkthin sample	181	89.5%	51 min	0.00%	A+
SEA to BOS · Bostonthin sample	172	76.0%	59 min	0.58%	B+
SEA to AUS · Austinthin sample	170	88.2%	55 min	0.00%	A+

Delay causes

What held SEA up in April

One category carries most of the weight here. Carrier accounts for 53% of the 103,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

Carrier
53%
National Airspace System
25%
Late-arriving aircraft
19%
Extreme weather
2%
Security
0%

The largest share of delay minutes, 53%, 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 55,000 of the 103,000 delay minutes reported here. The split is drawn from 102,668 reported delay minutes.

Cancellations are rare at 0.17%, below the national 0.90% 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.

Badly late arrivals are rare here: only 3.3% land an hour or more behind schedule, against 6.4% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

What to do with this

Flying from SEA in April

For a April trip through SEA: this is one of the better months to be flying from here, 85.6% on time with 0.17% cancelled. That is a base rate for the month as a whole; a single storm can still spoil a particular day.

Seattle-Tacoma International (SEA), the whole year
SEA in July69.2%
SEA in August73.6%
SEA in September82.9%
SEA in October82.9%
SEA in November81.9%
SEA in December74.0%
SEA in January81.6%
SEA in February84.4%
SEA in March80.2%
SEA in May82.2%
SEA in June78.1%

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