Southwest Airlines announced plans to operate daily nonstop flights between Charles M. Schulz–Sonoma County Airport (STS) in Santa Rosa, California, and Denver International Airport starting March 11, 2027. The airline will phase in this expansion beginning next month with flights running five days a week from Thursday through Monday, increasing to nearly daily service during the Thanksgiving and Christmas holidays in 2026.
Passenger Traffic and Airline Service Growth
Southwest began weekly nonstop Saturday flights from Sonoma County to Denver on April 7, 2026. Through June 2026, Southwest carried 53,899 passengers on its routes from Sonoma County, achieving load factors around 66-67%. June 2026 passenger volume at
Sonoma County Airport rose 24.5% from June 2025 to 92,759, and the airport served 409,425 passengers through June 2026, a 7.6% increase year-over-year and 29% above 2019 levels.
Alaska Airlines, Sonoma County’s largest carrier, recorded a 21% increase in passenger traffic to 303,673 during the first half of 2026, with 58,934 passengers in June alone and a 79% load factor. Delta Air Lines announced plans to begin twice-daily nonstop flights to Salt Lake City from Sonoma County starting October 6, 2026. American Airlines maintained 89 departures in June 2026, the same number as June 2025, but increased its load factor
from 70% to 86% by deploying smaller regional jets, carrying 13,748 passengers in June.
Airport Management Comments on Competition and Growth
Jon Stout, Manager of Charles M. Schulz–Sonoma County Airport, emphasized ongoing monitoring of airline performance amid rising competition. He noted the airport is on track to handle between 950,000 and 1 million passengers in 2026. Regarding Southwest’s service increase, a spokesperson stated, “We intentionally started small with our new service at (Sonoma County airport) (as we do with all new destinations), and we’re now maturing that service.” Stout said the airport plans to analyze monthly airline data to ensure all carriers maintain strong operations.
Fly Quiet Noise Reduction Program and FAA Departure Procedure Changes
To address
community noise concerns, Charles M. Schulz–Sonoma County Airport staff will present seven components of a proposed Fly Quiet program to the Sonoma County Aviation Commission on August 20, 2026. The commission will review potential noise reduction strategies before forwarding recommendations to the Sonoma County Board of Supervisors. Stout highlighted considerations regarding public disclosure of airlines’ noise performance ratings, noting, “How far do they want to take the shaming side of it?”
The airport is also awaiting Federal Aviation Administration (FAA) consultation on proposed changes to departure procedures. Consultants have submitted recommended procedures to the FAA’s online portal and discussions are
expected soon.
Passenger Growth and Airline Competition Impact
Passenger volumes increased notably after Southwest’s market entry and Alaska Airlines’ frequency growth, offsetting losses from Avelo Airlines, which ended service in May 2025. Competition on routes such as San Diego and Las Vegas has intensified, with Alaska and Southwest offering up to five daily flights to San Diego. Stout said the airport is augmenting its competitive route analysis by incorporating consultant findings alongside government data, stating, “Now that we actually have more competition, we’ll be looking at that on a monthly basis as well, because we want to make sure all of our carriers are strong.”
