Southwest Airlines is quietly building one of the busiest Hawaii operations in the US, and travellers who like low fares to the islands should take note. According to Cirium data, the airline has launched or will launch six new routes to Hawaii between March 2026 and March 2027, five of them from California.

The one outlier started this August: a nonstop from Las Vegas to Hilo on the Big Island. That route runs three to four times weekly on a 175-seat Boeing 737 MAX 8, stepping up to four or five weekly near the end of the year. The westbound flight takes just over six hours, leaving Las Vegas at 9:30 AM and landing in Hilo at 12:35 PM, with an overnight return. Vegas officials have long called their city the 'Ninth Island' because of the strong Hawaiian visitor base there, and this route formalises that bond.

The rest of the expansion comes out of California. Honolulu gained new links from Burbank (August) and Ontario (June), both currently scheduled through May. San Diego is the real growth story: daily Maui flights began in early March 2026 and run to at least early June, and in March 2027 Southwest will add twice-weekly services from San Diego to both Kona and Lihue on Kauai. Every new mainland route uses the same 737 MAX 8.

What's easy to forget is how big Southwest's inter-island network has become. This month alone it has scheduled nearly 1,500 flights between the islands, carrying over a quarter of a million seats. Its busiest corridor, Honolulu to Maui, runs seven or eight times a day, with four or five daily frequencies from Honolulu to Hilo, Kona and Lihue, plus daily Maui-Kona and Maui-Lihue flights. That's meaningful competition in a market once dominated by Hawaiian Airlines, and it often means cheaper hop-between-islands fares than travellers might expect.

For holidaymakers, the practical upshot is flexibility. If you're flying from the West Coast, you may no longer need to transit Honolulu at all — Hilo, Maui, Kona and Kauai are increasingly reachable nonstop. And once you're in the islands, mixing two islands on one trip is straightforward and affordable. Book the California routes early where they're seasonal (several currently only run into May or June), and watch for the new San Diego-Kona and San Diego-Lihue flights when schedules open for March 2027.