(CNS) – Thousands of Southwest Airlines passengers remained stranded Tuesday across Southern California as the airline’s winter woes worsened, leading to canceled and delayed flights throughout the nation.

As of 9:30 a.m. Tuesday, the airline had canceled 2,571 flights nationally, including several from Palm Springs International Airport and other airfields across Southern California, according the tracking website FlightAware. At PSP, a total of seven departing Southwest flights had been canceled by mid-morning Tuesday, with 16 others delayed.

At LAX, a total of 60 flights from all airlines had been canceled as of Tuesday morning, with 62 others delayed.

Stranded passengers were left with few alternatives, with the Southwest Airlines’ website listing all flights departing from Southern California as “unavailable” through Saturday.

Some flights were still departing from Palm Springs International Airport, LAX, John Wayne Airport, Hollywood Burbank Airport and Long Beach Airport, but passengers were being urged to check flight schedules.

As of Tuesday morning, 51 flights had been canceled at John Wayne Airport — including airlines other than Southwest — as were 41 flights from Burbank and 32 from Long Beach.

The airline issued an apology to stranded holiday travelers, stating that its operational challenges stem from last week’s historic winter storm.

“With consecutive days of extreme winter weather across our network behind us, continuing challenges are impacting our customers and employees in a significant way that is unacceptable,” according to a Southwest statement. “We are working with safety at the forefront to urgently address wide-scale disruption … And our heartfelt apologies for this are just beginning.”

On Monday, Southwest canceled more than 2,900 flights across the country, or about 70% of its scheduled total, according to FlightAware. By 6 a.m. Tuesday, Southwest canceled more than 2,500 more flights, which accounted for at least 60% of its schedule.

The airline’s CEO, Bob Jordan, told the Wall Street Journal that Southwest was planning to fly about one-third of its schedule Tuesday as it worked to catch up from the massive delays. Although the airline has continued to blame winter weather for the problems, some industry watchers have suggested that aging scheduling software played a major role in the delays.

Officials with the U.S. Department of Transportation issued a statement calling the Southwest situation “unacceptable.”

“USDOT is concerned by Southwest’s unacceptable rate of cancellations and delays and reports of lack of prompt customer service,” the department stated. “The department will examine whether cancellations were controllable and if Southwest is complying with its customer service plan.”

Southwest Airlines said it was fully staffed late last week and prepared for the approaching Christmas weekend when severe weather swept across the continent.

“We’re working with safety at the forefront to urgently address wide- scale disruption,” airline officials stated.

“On the other side of this, we’ll work to make things right for those we’ve let down,” the airline stated.

Impacted travelers can find more information a southwest.com/traveldisruption.

Passengers Stranded Across SoCal as Southwest Airlines Woes Worsen