Denver International Airport reopened shortly after 7 p.m. Wednesday, after it was closed most of the day by a blizzard that forced the cancellation of some 1,300 flights.

Only a few flights are expected to fly in and out of Denver the remainder of Wednesday.

The westbound lanes of Peña Boulevard reopened about 4 p.m. while the eastbound lanes reopened at about 5:44 p.m. Earlier, officials said the route was impassable and urged passengers already at the hub to stay put.

At about 2 p.m. United Airlines and Southwest Airlines canceled all remaining scheduled flights in and out of the airport.

DIA spokesman Heath Montgomery said officials believe the last time the airport was closed because of snow was December 2006 after back-to-back blizzards.

The Federal Aviation Administration on Wednesday morning grounded all incoming and outbound flights at about noon because adverse weather conditions.

The airport’s closure prompted long queues at airlines’ customer service counters where frustrated passengers are being told it could be days before they are able to be rebooked.

SNOW TOTALS: How much did your area get?

By midday, about half of all flights scheduled Wednesday had been canceled before the closure was enacted and the majority of scheduled trips were called off.

The airport’s shuttering followed an extended power outage at the hub on Wednesday morning that stymied some airport operations for several hours — including fuel pumps, deicing systems and passenger train service between the concourses for about 15 minutes.

Flights were grounded as Xcel Energy worked to resolve the situation. Electricity has since been restored.

Strong, gusting winds upwards of 45 mph have been unrelenting, blowing heavy snow across the airport’s campus and creating hazardous conditions for motorists trying to reach the main terminal.

POWER: Storm causes power outages for thousands of people

Some passengers sat for hours on aircraft waiting to depart on Wednesday morning only to be told their flights were canceled and the airport closed.

Ruth Ann Nickell’s flight to Tucson was delayed for three hours before Southwest Airlines boarded her.

“They finally got us on the plane at like 10:45 (a.m.),” she said. “As soon as I sat down I got a text alert that the flight was canceled. We had to de-plane, rebook and pick up our bags and start all over again.”

Nickell, of Indiana, said about 1:30 p.m. that she was standing at the Southwest Airlines ticket counter, where she had been for more than two hours. She has been told she will be rebooked on a Friday flight at the earliest.

“It is very frustrating,” said Nickell, who was heading to see her children and grandkids. “I haven’t seen them in a year and half. This is really heartbreaking.”

MORE: Snow totals around the Denver region.

A clerk at the Westin Denver International Airport said it was fully booked and had a “very long” waitlist.

Pete Rossi said he was stranded in one of the airport’s underground shuttle trains when the power went down.

‘There was no information communicated,” he said. “(Hundreds) of folks (were) underground with the train doors opening and closing.”

Rossi finally boarded his flight to Atlanta more than three hours after it was scheduled to depart. At 11 a.m. he said was still waiting to take off.

He called the ordeal frustrating and confusing.

The fuel tanks to the north side of DIA’s property were without power until just after 9:15 a.m. because of the power outage, hindering the ability to pump fuel to the concourses.

DIA also was unable to pump deicing fluid to trucks during the power outage, though the airport did have a limited supply in the trucks that was available for use.

Eddie Oliver Smith’s flight to Chicago was delayed after he had boarded at 5:30 a.m. About four hours later, he was allowed to get back on.

He called the intermittent electricity in the terminal “scary.”

“The screens went off in gates C, all the computers went down,” Smith said, “then came back on.”

Montgomery urged travelers to anticipate delays, check their flight status early and often, and double their normal drive time to the airport.

Just before 11 a.m., the airport reported its parking garages were full. Officials urged travelers to use the economy or shuttle lots.

Peña Boulevard has also seen intermittent closures because of crashes.

The airport is employing full deicing operations for the duration of the snow. Passengers should anticipate spending additional time on the aircraft prior to departure, officials said.

The average deicing time is 16 minutes, but can vary based on the type of aircraft.

Frontier Airlines issued a winter storm alert on Wednesday, listing canceled flights. The Denver-based carrier offered refunds to customers whose flights were canceled and allowed waived fees for some customers scheduled to travel Wednesday.

“The issue this week is that it’s spring break so it might be hard to get people rebooked since a lot of flights are booked,” said Jim Faulkner, a Frontier spokesman.

Southwest Airlines and United Airlines are offering similar change fee waivers.

Around the region

Centennial Airport on Wednesday morning suspended operations and, as of 9 a.m., airport officials said they had hoped to reopen in two to three hours.

“The visibility for snow crews and other operations pose a hazard,” said Deborah Grigsby Smith, a Centennial Airport spokeswoman. “We do have snow crews on standby. They’re assessing the situation.”

The last time Centennial Airport suspended operations was in December 2006 when 34 inches of snow fell in 34 hours, she said.

Colorado Springs Airport reported minimal disruption from the storm. Aside from the flights being canceled to and from Denver, other flights were departing on time, said Nathan Lavin, spokesman for the Colorado Springs Municipal Airport.

“The snow accumulation has been pretty minimal here,” he said, adding the airport has received about 2 to 3 inches of snow.

The majority of flights in and out of Aspen/Pitkin County Airport were canceled Wednesday.

Eagle County Regional Airport was also reporting a long list of canceled flights.

Jesse Paul: 303-954-1733, jpaul@denverpost.com

Denver Post online producer Kourtney Geers contributed to this report.