San Diego has record capacity; Southwest & Alaska Airlines add 2.5 million seats in 1 year

California has more available seats than any other US state. Cirium schedule data shows that 32 airports in the Golden State have scheduled passenger service, which, of course, includes San Diego (SAN).

In the second of 2026 (July-December), Cirium data shows that SAN has 19.10 million two-way seats. Compared to the same six months in 2025, capacity has risen by a substantial 14%, with 2.28 million additional seats. SAN is thus among the world’s fastest-growing major airports.

Part of the increase is from welcoming multiple airlines recently. They include Breeze Airways in 2024, along with Copa Airlines and KLM in 2025. It was also achieved despite the now-defunct Spirit pulling out in 2025, which was also when Allegiant Air did so. But the considerable growth is primarily due to two incumbent operators.

Southwest & Alaska Airlines double down on SAN

With 7.18 million two-way seats and 37% of the airport’s total, Southwest is by far the largest airline at SAN. Capacity grew by 21% year-over-year, with 1.25 million seats added. This considerable growth, in very little time, means that SAN has jumped two places to become Southwest’s 10th most-served airport.

The hybrid airline now has 45 routes from SAN, of which 43 are domestic and two are international. Compared to the second half of 2025, nine markets have been added: Boise, Bozeman, Ft. Lauderdale, Kahului, Puerto Vallarta, Santa Barbara, Santa Rosa, Seattle and Spokane.

Southwest has added multiple routes to West Coast destinations. It is increasingly facing Alaska Airlines, whose capacity at SAN has jumped by 36%, with 1.22 million seats added year-over-year. 49 routes are available, which now include Dallas DFW, Oakland, Raleigh/Durham, Santa Barbara and Tulsa. Alaska Airlines and Southwest compete head-to-head to 27 airports.

Domestic and international capacity at record highs

Between July and December 2026, Cirium data shows that SAN has 18.34 million two-way domestic seats, up by 14% year-over-year. This is a record volume, with this market now accounting for 96% of the airport’s total capacity.

Flights to 76 domestic airports exist, which are in 36 states. With 4.40 million seats, California accounts for 23% of SAN’s capacity. SAN has flights to ten airports in the Golden State, and four made the top 10 list.

The international market has grown too. A record 758,500 two-way seats now exist, which is up 8% over the past year. Flights are available to Amsterdam, Calgary, Los Cabos, London LHR, Montreal, Panama City, Puerto Vallarta, Tokyo NRT, Toronto and Vancouver.

Particularly strong growth has been seen to Amsterdam (+56% more seats), London LHR (+17%) and Panama City (+17%). KLM now serves SAN on a year-round basis (3-weekly), while British Airways has more peak summer flying (2-daily flights every day) and now has a daily operation in the winter. Copa Airlines has grown frequencies to Panama City.

Most of San Diego’s top 10 destinations have grown by double digits in the past year. This includes San Francisco, which remains the most-served market, with capacity up by a quarter. 168-weekly flights exist in September, provided by United (58), Alaska Airlines (56), Southwest (47) and Frontier (7). All four airlines have grown, but particularly Southwest (up from 31-weekly flights last year).