The spring months are March, April, and May. In this period, Southwest plans an average of 4,016 daily flights (takeoffs and landings combined). Its offering has increased marginally year-over-year.

Examining Southwest’s schedule submission to Cirium Diio indicates that the increasingly evolving carrier plans 929 routes this spring. This is based on having a minimum of four departures. Some 73 routes are international, while 856 are domestic. They include 42 additions, some of which are bound to make my weekly article that’s full of celebration (see the most recent edition).

Southwest’s 42 New & Returning Routes This Spring

Credit: GCMap

They are shown on the map above. For such articles, I usually always include a full breakdown of each airport pair, providing details including the start date, frequency, equipment, whether the airline has previously served it, head-to-head competition, etc. However, for space reasons, this has not been done here.

The 42 additions are based on analyzing all of Southwest’s routes with four or more departures between January 2025 and February 2026, and comparing that with what’s available from March to May 2026. Naturally, routes have ended too; they’ll be covered separately.

Four cities have joined its map: Anchorage, Knoxville, St. Maarten, and Santa Rosa. Clearly, Anchorage is of historic significance to Southwest, as it marks its debut in Alaska after 50+ years. More on that below.

The average stage length of the 42 routes is 872 nautical miles (1,615 km). That’s 28% longer than the airline’s average length across its entire network this spring. It is driven by some long markets: Anchorage to Denver and Las Vegas, Kansas City to Punta Cana, and San Diego to Kahului. Yet, several additions are exceptionally short, including Chicago Midway to Milwaukee; virtually all passengers will connect elsewhere.

Southwest To Anchorage

Credit: Wikimedia Commons

On May 15, the carrier will begin flying from both Denver and Las Vegas to Anchorage. It’ll serve both markets daily on the 175-seat Boeing 737 MAX 8. The final departure of the season will leave Alaska on September 15.

It’ll compete head-to-head with Alaska Airlines and United Airlines from Colorado, becoming the first time in five years that the market will have a trio of operators. It is not among United’s ten longest MAX routes. Frontier operated briefly in 2021, although it had regular flights for years until 2014. Southwest’s arrival means a record seven daily flights will be available on Saturdays during the peak summer of 2026.

Fortunately, Southwest will benefit from its massive connectivity via Denver. After all, the US Department of Transportation shows that it is the carrier’s most-served airport by passengers, flights, and transit traffic. Las Vegas is similarly placed: it ranks second for the three measures.

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A Look At San Diego To Kahului

Credit: Shutterstock

At 2,208 nautical miles (4,089 km) each way, San Diego to Kahului will be Southwest’s new 10th-longest city pair by distance this spring. Served daily, the first flight left California on March 5. The route runs daily on the MAX 8.

It was previously part of its network in 2021 and 2022, when the DOT shows that it only filled 46.5% of seats. Being served during the pandemic was primarily responsible. As before, it’ll be the airline’s second route from San Diego to Hawaii, joining flights to Honolulu.

Southwest has five other additional San Diego routes this spring: Bozeman (only served briefly), Puerto Vallarta, Santa Rosa, Seattle, and Spokane. It means the carrier will have 41 routes from the California airport in this period, with an average of 110 daily flights (takeoffs and landings combined). Its movements have risen by 14% compared to the same three months in 2025, with the growth partly in response to Alaska Airlines’ expansion there.