Earns-AirlinesStarting in March, Southwest will offer four daily flights from Colorado Springs to Denver International Airport, three to Dallas Love Field Airport and two each to Las Vegas, Phoenix and Chicago Midway International Airport.

Hundreds of Southwest Airlines flights at Denver International Airport were canceled over the weekend as the airline reported operational issues.

As of 5 p.m. Sunday, 148 Southwest flights were canceled and 130 were delayed at DIA, according to Flight Aware. That accounts for more than 90% of DIA’s 163 total canceled flights and makes DIA the airport with the most cancellations worldwide Sunday afternoon. 

Another 102 Southwest flights were canceled and 172 were delayed at DIA on Saturday.

Nationally, Southwest Airlines has canceled 1,880 flights and delayed 2,066 flights on Saturday and Sunday, according to Flight Aware.

In a Facebook post, Southwest Airlines attributed the cancellations to “Air Traffic Control issues and disruptive weather,” however, Denver’s forecast on Saturday and Sunday called for sunny conditions and temperatures in the 60s.

The Federal Aviation Administration said in a tweet there have been no air traffic staffing shortages since Friday. The administration also blamed the cancellations on weather, in addition to military training and aircraft and crews "being out of place."

The Southwest Airlines Pilots Association said in a news release the cancellations were a result of “poor planning” from the airline.

"Our pilots are not participating in any official or unofficial job actions,” the labor union said. “Our pilots will continue to overcome SWA management’s poor planning, as well as any external operational challenges, and remain the most productive pilots in the world.”

No other airlines experienced high volumes of cancellations over the weekend, according to Flight Aware. American Airlines had the second-highest number of cancelations in the U.S. on Sunday, with only 63 flights canceled.

In the Facebook post, Southwest Airlines said it is trying to recover its operations by Monday.

“We appreciate your patience as we accommodate affected customers as quickly as possible,” the airline said.

Customers whose flights were canceled are asked to rebook their flights on southwest.com. The airline’s customer service wait times are longer than usual, the airline said.