The mercury also dropped into negative territory in Milwaukee, St. Louis and Chicago, which set a record for the date at minus 16. Wind chills across the region were 40 below and colder. Records also fell in Oklahoma, Texas and Indiana.

Authorities in Indiana and Kentucky -#8212; where temperatures dropped into the single digits and below, with wind chills in the minus 20s and worse -#8212; warned people not to leave their homes at all unless they needed to go someplace safer.

Utility crews in Indiana worked to restore power to more than 40,000 customers affected by the weekend storm and cautioned that some people could be in the cold and dark for days.

Several deaths were blamed on the snow, ice and cold since Saturday, including the death of a 1-year-old boy who was in a car that went out of control and collided with a snowplow Monday in Missouri.

In the eastern United States, temperatures in the 40s and 50s Monday helped melt piles of snow from a storm last week, raising the risk that roads would freeze over as the cold air moved in Monday night, said Bob Oravec from the Weather Prediction Center in College Park, Md. The snap was set to be dramatic; Springfield, Mass., enjoyed 56 degrees Monday morning but faced an overnight low of 6.

More than 3,700 flights were canceled by late Monday afternoon, following a weekend of travel disruption across the nation. Airline officials said de-icing fluid was freezing, fuel was pumping sluggishly, and ramp workers were having difficulty loading and unloading luggage.

JetBlue Airways stopped all scheduled flights to and from New York and Boston on Monday. Southwest ground to a halt in Chicago earlier in the day, but by the evening, flights resumed in "a trickle," a spokesman said.

Locally, San Francisco International Airport had 24 cancelled departures and 32 cancelled arrivals on Monday by 5 p.m. At Oakland International Airport, five departing flights and eight arrivals had been cancelled.

"Airports back east are doing the best they can but it's a total mess," said Scott Wintner, spokesman for the Oakland airport. "Planes are super full because people are headed home, back to school after the holidays.

Delays of up to two hours were not uncommon Monday at Bay Area airports. Wintner suggested that people check the status of their flight before heading to the airport.

"That way, if it's cancelled, they can rebook from the comfort of their home," he said.

And with airline call centers reportedly so backed up that they're putting people on hold for hours at a time, he suggested doing as much online as possible.

Sonoma County residents flying back from visits to the East Coast this weekend found themselves caught up in the mess.

Orozco, a pastor at Santa Rosa Alliance Church, was scheduled to fly home on Saturday from a trip to visit family in the Washington, D.C., area. When he arrived at the airport for the 12:45 p.m. flight, he learned it had been delayed for two hours. Eventually, it was cancelled. By then, he'd spent the whole afternoon in the airport.

"Fortunately, my wife was still there (on the East Coast)," Orozco said. He spent the night at his mother-in-law's home, but tensions were running high back at Reagan National Airport, where stranded travelers searched for alternative routes home.

"One of the things I learned is that you have to be patient, you have to speak wisely when you talk to the people at the (ticket) counter," he said. "They are under pressure, and if you're not careful about how you say things, there might be an explosion."

Orozco recalled having a tense conversation with an airline worker at a ticket counter as he tried to get on another flight. She finally agreed to look up a flight for him, and as she did so, she began singing a hymn, "How Great Thou Art." It is one of Orozco's favorite hymns.

He told her so, and they laughed.

"I was amazed," he said. "Here I was, complaining, and getting upset, and she started singing one of my favorite hymns. It was a gift from God."

He missed a Sunday service he was scheduled to lead at his church, but was able to land a seat on a flight early Monday morning and arrived safely in San Francisco at 10:30 a.m.

In the future, Orozco said, he'll probably add a couple extra travel days to his vacations back east -#8212; just in case.

The Associated Press contributed to this story.