Carrier performance at one airport

WN→SJC

Southwest Airlines at Norman Y. Mineta San Jose International

Departures: 26,391
Period: September 2025 to August 2026
Routes: 25
Rank here: #6 of 7

Southwest Airlines at San Jose lands a B+, 2 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 50 minutes on average. That rests on 26,391 flights, of which Delta Air Lines flew 2,995 at 92.4% on time.

Measured against the airport rather than the country, Southwest Airlines runs 3 points behind the 81.9% weighted average across all carriers at SJC. That is the comparison worth making: every operator here works the same runways, the same airspace and the same weather.

On time

78.8%

26,188 completed departures

Avg delay

48 min

Across delayed flights only

Cancelled

0.56%

At SJC, this carrier only

Rank here

Of 7 carriers clearing the floor at SJC

These figures cover 26,000 flights between September 2025 and August 2026. The median arrival is 5 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.

Against the competition

Every carrier at SJC, ranked

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 92.4% of the time; Frontier Airlines manages 75.8%. Sample sizes sit next to every figure, because a two-point gap across 368 flights means less than a ten-point one.

On-time performance of all carriers departing SJC
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	2,995	92.4%	73 min	1.20%	A
United Airlines	1,510	87.8%	62 min	0.46%	A+
SkyWest Airlines	6,558	86.9%	63 min	0.50%	A+
Alaska Airlines	3,070	84.4%	51 min	0.91%	B+
American Airlines	1,812	83.1%	88 min	1.49%	B
Southwest Airlines (this page)	26,391	78.8%	48 min	0.56%	B+
Frontier Airlines	368	75.8%	56 min	2.45%	B

The spread between Delta and Frontier is 17 points, wide enough that it should decide the booking. On a hundred trips that is 17 more arrivals inside the on-time window.

Route by route

Where Southwest Airlines flies from SJC

Southwest Airlines operates 25 routes out of SJC with enough volume to report. Route records inside one carrier at one airport still spread widely, because a short shuttle and a transcontinental have very different exposure to a late inbound.

Southwest Airlines routes from SJC
Route	Flights	On time	Avg delay	Cancelled	Grade
SJC to SAN · San Diego	3,745	66.5%	46 min	0.96%	C+
SJC to LAS · Las Vegas	3,246	80.6%	55 min	0.49%	B+
SJC to SNA · Santa Ana	2,678	86.6%	46 min	0.78%	A+
SJC to BUR · Burbank	2,133	84.7%	50 min	1.27%	B
SJC to PHX · Phoenix	1,869	77.7%	49 min	0.64%	B+
SJC to LAX · Los Angeles	1,867	76.8%	47 min	0.64%	B+
SJC to DEN · Denver	1,520	74.8%	52 min	0.46%	C+
SJC to ONT · Ontario	1,318	82.4%	46 min	0.15%	B+
SJC to LGB · Long Beach	1,251	84.4%	45 min	0.16%	B+
SJC to AUS · Austin	1,108	73.9%	47 min	0.36%	C+
SJC to PDX · Portland	923	80.0%	49 min	0.00%	B+
SJC to SEA · Seattle	904	75.6%	46 min	0.00%	B+
SJC to MDW · Chicago	526	84.6%	31 min	0.19%	B+
SJC to HNL · Honolulu	445	75.6%	46 min	0.22%	B+
SJC to DAL · Dallas	409	83.3%	49 min	0.98%	B+
SJC to HOU · Houston	365	90.1%	30 min	0.27%	A+
SJC to BOI · Boisethin sample	330	78.7%	46 min	0.00%	B+
SJC to EUG · Eugenethin sample	271	71.2%	43 min	0.00%	C+
SJC to BNA · Nashvillethin sample	246	87.7%	37 min	0.00%	A+
SJC to RNO · Renothin sample	243	95.9%	36 min	0.00%	A+
SJC to BWI · Baltimorethin sample	242	81.0%	31 min	0.00%	B+
SJC to GEG · Spokanethin sample	238	76.1%	39 min	0.00%	B+
SJC to SLC · Salt Lake Citythin sample	208	78.7%	56 min	0.48%	B+
SJC to PSP · Palm Springsthin sample	198	80.0%	55 min	1.01%	B
SJC to OGG · Kahuluithin sample	105	90.5%	35 min	0.00%	A+

Departure window

Best time of day for this operation

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 29 points, against 17 points between the best and worst carrier.

5am–8am4,508 flights95.6%
8am–11am5,603 flights89.3%
11am–2pm4,567 flights78.8%
2pm–5pm4,602 flights67.4%
5pm–8pm4,374 flights66.8%
8pm–5am2,737 flights67.8%

Scale runs 60% to 100%.

Book the early departure. Flights leaving between 5am–8am arrive on time 95.6% of the time, against 66.8% for the evening window. That is 29 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 5,603 flights scheduled in it.

Across the year

Seasonal pattern

Darker means more delays. Figures are on-time percentages.January best, June worst

June is the worst month at 67.8% on time, 22 points below January, the best at 89.9%. 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. July was the busiest month here, with 2,383 flights.

Delay causes

What holds this operation up

Late-arriving aircraft
55%
Carrier
23%
National Airspace System
21%
Extreme weather
1%
Security
0%

55% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 264,000 reported delay minutes here, that single category outweighs weather by 55 to one. The split is drawn from 263,817 reported delay minutes.

Cancellations are rare at 0.56%, 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.

5.0% 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.

26,391 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.

Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 89.9% on time and June 67.8%, a swing of 22 points. If the dates move at all, move them out of June before you think about anything else. 26,188 completed flights over 12 months sit behind that.

Common questions

Southwest Airlines at SJC

How often is Southwest Airlines at SJC delayed?

About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.2% of the 26,391 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 50 minutes on average.

Which airline is most reliable on Southwest Airlines at SJC?

Delta Air Lines leads at 92.4% on time across 2,995 flights. Frontier Airlines is at the other end on 75.8%, a gap of 17 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

What time of day has the fewest delays on Southwest Airlines at SJC?

The 5am–8am departure window is the strongest at 95.6% on time. The 5pm–8pm window is the weakest at 66.8%, 29 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.

How bad are June delays on Southwest Airlines at SJC?

June is the weakest month at 67.8% on time, compared with 89.9% in January. Across the year that is 22 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures