Staring out the window at the clear blue skies above her grandmother’s home in Kansas City, Mo., on Friday, Tiffany Barrington had a hard time imagining the weather chaos swirling a few hundred miles to her north that was keeping her from her best friend’s wedding-dress fitting in Chicago.

“It’s totally amazing here, it’s 50 degrees, it’s nice. I don’t even need a jacket,” said Ms. Barrington, 25, a philosophy major at Northeastern Illinois University, whose morning flight to Midway International Airport had been canceled. She was rebooked to travel Saturday. “But it’s supposed to be a mess up there.”

That mess of dense fog and flash flooding prompted a cascade of flight cancellations and delays at one of the nation’s most significant aviation crossroads, stranding thousands of passengers already exhausted by a week of weather-related snarls from coast to coast.

Rising temperatures in Chicago were quickly melting the half-foot of snow and ice that had accumulated earlier in the week The region was also bracing for one to three inches of rain through Saturday night in a weather system expected to pound the Northeast with rain by Sunday, said a National Weather Service meteorologist, Amy Seely.

A Chicago Department of Aviation spokesman, Greg Cunningham, was not encouraging. “It doesn’t appear to be looking too much better in the near future in terms of weather,” Mr. Cunningham said, adding that O’Hare International Airport had seen more than 150 canceled flights Friday and Midway had more than 20. Flights leaving O’Hare were delayed by at least 90 minutes on average by late Friday afternoon, he said.

At Midway, vacillating temperatures and relentless precipitation caused a Southwest Airlines jet bound for Los Angeles to skid off the taxiway and become stuck in snow and ice early Friday morning. No injuries were reported, and passengers from that flight were flown on different aircraft later in the morning, said Olga Romero, a Southwest spokeswoman.

Elsewhere, the wintry weather was deadly. Six traffic deaths on Friday were attributed to icy conditions in Indiana, where stretches of major highways were closed because of ice early Friday.

Nature was not to blame for all air traffic problems. A slowdown on Friday at Hartsfield-Jackson International Airport in Atlanta was prompted by an air-traffic-control equipment failure that, for a time, allowed the airport to land just one plane at a time.

“I was very lucky to get out of Indianapolis before the storm moved in there, but now I’ve been stuck here for four or five hours,” said John Blankenship, 28, who was waiting Friday to board a plane to Dothan, Ala., to visit his mother. “I was expecting a one-hour layover. But the plane we’re supposed to be leaving on hasn’t arrived yet.”

The Federal Aviation Administration’s online airport map showed Chicago and Atlanta as the only two trouble spots Friday, but that did not reflect travelers playing catch-up across the country from snow and ice storms earlier in the week.

In Salt Lake City, for instance, more than 200 passengers slept in the airport on Thursday night while thousands of others were placed in nearby hotels thanks to a snowstorm that paralyzed the city on Christmas Day.