Southwest Airlines will begin nonstop service between Charles M. Schulz–Sonoma County Airport (STS) and Denver in late July 2026, with plans to increase flights to daily by March 11, 2027.
Southwest’s Flight Frequency Growth and Passenger Traffic
The airline initially launched weekly nonstop flights to Denver from Sonoma County on April 7, 2026. Southwest notified Sonoma County Airport officials of its intent to expand the Denver route starting March 11, 2027, upgrading from a current weekly service to daily operations.
Frequency will ramp up in multiple phases: five flights per week (Thursday through Monday) in August and September 2026, increasing to nearly daily flights during the Thanksgiving
and Christmas holiday periods, and additional service on select days between those months.
Southwest carried 20,077 passengers in June 2026 across flights from Sonoma County to Denver, Burbank, San Diego, and Las Vegas. Year-to-date through June, Southwest transported 53,899 passengers with monthly load factors of 67% in June and 66% for the first half of 2026.
Sonoma County Airport handled 92,759 passengers in June 2026, marking a 24.5% increase over June 2025 and a 27.2% increase compared with June 2019. Through June 2026, the airport recorded 409,425 passengers, up 7.6% from the same period in 2025 and 29% from 2019.
The airport projects handling between 950,000 and 1 million passengers during 2026.
Other Airlines and Route Developments
Alaska Airlines remains the largest carrier at Sonoma County, increasing passenger traffic by 21% to 303,673 passengers in the first half of 2026. Alaska carried 58,934 passengers in June 2026 with a load factor decline from 83% in June 2025 to 79% in June 2026.
Delta Air Lines announced plans to launch twice-daily nonstop flights from Sonoma County to Salt Lake City on October 6, 2026. Alaska Airlines is resuming seasonal flights to Palm Springs on September 10, 2026.
American Airlines carried 13,748 passengers in June 2026, a
4.3% increase from the previous year, although its first-half total declined by 6.4% to 51,853 passengers. The airline operated the same number of June departures as in 2025 but replaced larger 120-seat Airbus A319 jets with smaller 76-seat Embraer E175 regional aircraft.
Avelo Airlines ceased service at Sonoma County in May 2025, contributing to a reduction in passengers early that year before Southwest and Alaska frequency increases drove growth.
Sonoma County Airport’s Noise Reduction and Operational Plans
In response to rising community noise complaints, Sonoma County Airport is developing the Fly Quiet noise-reduction program. Airport staff will present seven components of this program to the Sonoma County Aviation
Commission on August 20, 2026, with details including costs and noise modeling requested by commissioners on June 18, 2026.
The Fly Quiet program includes policies on airline noise-performance report cards and ongoing discussions on how openly to publish airline noise ratings. Airport Manager Jon Stout questioned the extent of publicly identifying carriers with lower noise performance, asking, “How far do they want to take the shaming side of it?”
Separately, the airport and its consultants await discussions with the Federal Aviation Administration regarding recommended changes to departure procedures, with submissions expected by early August 2026.
Official Statements and Competition Monitoring
Southwest Airlines spokesperson Chris Perry
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.” Airport Manager Jon Stout noted, “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.”
Competition has intensified on nonstop routes such as San Diego and Las Vegas, with both Alaska and Southwest serving San Diego, resulting in as many as five daily flights to that city from Sonoma County. The airport monitors such
competitive routes monthly and seeks to enhance data through consultants beyond government statistics, which have a 60-day delay.
