(CNN) -- Parts of the eastern United States that have experienced bitter temperatures aren't going to escape the harsh conditions anytime soon.
The National Weather Service said a low pressure system will draw warm, moist air from the Gulf of Mexico up into sub-freezing temperatures in Kentucky and Tennessee, introducing the threat of freezing rain that could coat roads, trees and power lines.
The weather service said the freezing precipitation will start as snow and gradually change into sleet and freezing rain by Wednesday and into Thursday morning.
Up to half an inch of ice is expected to accumulate across Kentucky and Tennessee and possibly into northern Mississippi and Alabama, raising the risk of downed power lines for residents across the region.
Winter storm warnings are in effect across much of Kentucky and southern Indiana, according to the National Weather Service.
"It's going to be a mixed bag" of snow, sleet, and freezing rain, meteorologist Ted Funk said. "That's going to provide some very hazardous driving conditions overnight and into Thursday morning."
There have been dozens of accidents in Mississippi and Alabama because of an ice storm, according to emergency management officials in both states.
Two people died in a wreck on an icy bridge in Alabama on Wednesday, officials said, and another died in a car accident in Mississippi.
AirTran Airways warned that the wintry weather could result in flight delays and cancellations, according to a company statement.
AirTran passengers scheduled to travel either to or from Atlanta, Georgia, between 7 p.m. Wednesday and noon Thursday will be permitted to change their reservation without penalty as long as the travel is completed within three days of the originally scheduled departure date, the statement said.
Areas from Minnesota to Ohio to New York have seen more than a foot of snow in the past several days.
The harsh weather stranded about 300 people in Canada Tuesday after what a local official called the most brutal storm to hit the Ontario region in more than two decades.
Some people had been stuck in their vehicles for more than 24 hours after blinding snow piled up so high that opening vehicle doors proved nearly impossible.
"You really felt almost despair," said Brandon Junkin, who spent almost 24 hours stranded before being rescued Tuesday afternoon after he heard a helicopter hovering over his immobilized truck. He had run out of gas and had nothing other than a blanket to help him through the ordeal.
The Canadian military assigned a CC-130 Hercules airplane and two CH-146 Griffon helicopters to the search and rescue effort, which also included snowmobiles and four-wheel-drive vehicles from the provincial police.
Ontario Provincial Police initially reported that about 360 vehicles and about 300 people had been stranded near Sarnia on Highway 402, a major thoroughfare linking the U.S.-Canada border to London, Ontario.
By Wednesday, officials said everyone had been rescued.
"It's been a pretty interesting experience for the last two days here," Sarnia police Sgt. Paul Mullins said. "In 23 years, I haven't seen anything like this."
Some residents offered up their homes and food to stranded motorists, Mullins said.
On Tuesday, record lows were set from Virginia to Florida. High temperatures were 30 degrees below average for this time of year.
But Florida's winter fruit and vegetable crops have apparently survived the freezing temperatures without too much damage, industry officials said Tuesday.
"We've had reports of frozen fruit scattered around the state," said Andrew Meadows, spokesman for the Florida Citrus Mutual, cautioning that the situation could have been worse. Some growers are cutting some slush ice, but overall, we're getting fairly favorable reports."
Meadows said the ridge region, which is southern Polk County, came through in decent shape while in the Indian River region -- known for its grapefruit production -- there have been additional reports of iced fruit.
"We do have damage reports, but we can't quantify it right now," he said. "To what extent the damage is, we're still analyzing that."
Meadows said many growers will begin harvesting early, taking frozen fruit off the trees for delivery to processing plants, because once temperatures begin warming again, the fruits will drop off the trees themselves. He noted that the association uses U.S. Department of Agriculture numbers issued each month to determine how crops were affected and that the most accurate numbers may not turn up until February's report.
Hendry County Extension Director Gene McAvoy said citrus crops in Southwest Florida fared all right.
"There was some slight damage to citrus, but citrus seems to have done pretty well," he said. "We had significant damage to vegetables around Southwest Florida with a number of tomato, pepper, eggplant, squash and other vegetable fields killed or severely frozen back. Not as bad as last year as in a number of fields; the plants had only had the tops frozen, but plants should survive and produce a crop depending on weather over the next few weeks."
McAvoy added that survival in younger plants seemed to be higher than in more mature plants approaching harvest.
He also said corn and beans were hit hard in Southwest Florida and around Belle Glade and that sugar cane will suffer some yield reduction.
CNN Radio's Greg Black, CNN meteorologists Chad Meyers, Angela Fritz and Rob Marciano and CNN's John Couwels and Vivian Kuo contributed to this report.