Crews clear snow from the runways at Reagan National Airport near D.C. last week as planes sit at their gates, grounded by the snow. (Shawn Threw/EPA)

Thanks to a seemingly endless barrage of snow, ice and brutal cold, this winter has seen the worst stretch of air travel in recent memory.

So far this year, more than 68,000 flights have been canceled, according to FlightAware. There have been more cancellations in the first two months of this year than during any three-month span since January 2011.

It has been a progression of nightmares, with scores of flight cancellations and delays among the problems caused by winter storms that repeatedly battered the Midwest, Northeast and the South.

January was the worst single month for flight cancellations in at least three years, with 39,991 flights halted. February isn’t over yet, but it already has 28,588 canceled flights. Overall, there have been more than 87,000 cancellations since Dec. 1 to go with hundreds of thousands of delayed flights.

Take Chicago’s O’Hare International Airport. It is among the busiest airports in the country, ranking second only to Atlanta’s Hartsfield International in recent years, according to the Department of Transportation’s Bureau of Transportation Statistics.

In January, as nearly three feet of snow pounded Chicago, more than 5,000 flights through O’Hare were canceled, reports Mark Duell, FlightAware’s vice president for operations. That was the most at any U.S. airport that month (the runner-up, Atlanta, had 1,800 cancellations).

“This is a harder winter than in previous years,” said Karen Pride, spokeswoman for the Chicago Department of Aviation, which operates O’Hare and Midway International airports. “This has been a very sustained, harsh harsh winter … there’s been a lot more snow.”

And cancellations at key hubs can have a ripple effect that reaches areas far from the snowy weather. The top destinations for flights from O’Hare in 2012 (the last year for which BTS data was available) were airports in New York, Los Angeles, San Francisco and Dallas/Fort Worth.

Travelers have been helped in recent years by the proliferation of airline or air travel smartphone apps and increased access to notifications, Pride said. As a result, fliers can find out with more notice about a canceled flight than they could have a decade ago, choosing to stay home and keeping airports from becoming massively overcrowded.

“We will do anything possible to avoid real-time cancellations,” Rob Maruster, chief operating officer of JetBlue, told Time for its new cover story (behind the paywall). “Nobody likes people standing in the airport watching real-time cancellations happen.”

The problems started at the beginning of the year with heavy and persistent snow in Chicago and its suburbs. Snowfall in the Midwest was soon followed by winter storms across the Northeast, which gave way to brutal cold across much of the U.S. that made it difficult to refuel planes or keep ground crews working outside.

Winter storms popped up again in late January and yet again in early February, with major problems last week stretching from ice-coated Southern states on up to the snow-filled streets of the Northeast. (It got so bad last week that states of emergency were declared from Louisiana to New Jersey.) And parts of New England as well as New York and Pennsylvania just dealt with yet another wintry blast  over the weekend.

This month, the airports seeing the biggest problems have been those hit by the icestorm in the South and the snow in the Northeast and Chicago. The airport with the most cancellations so far was Charlotte, with nearly 3,500, followed by Newark, O’Hare, Atlanta, LaGuardia and Philadelphia.