MIAMI: A freezing winter storm that has already sent temperatures plunging on much of the US east coast was Tuesday threatening usually balmy Florida, forecasters warned.

Just weeks after a "polar vortex" brought some of the coldest weather in decades to the eastern half of the United States, parts of the country are again in the throes of another vicious blast of cold air.

New Jersey, scene of Sunday´s NFL Super Bowl, was struggling in temperatures of 16 degrees Fahrenheit (-9 Celsius) on Tuesday, and the biggest spectacle in the US sporting calendar is being billed as possibly the coldest in the Super Bowl era.

But the cold front is spreading unusually far southward, forecasters say.

The National Weather Service said: "The strong cold front that is now off the east coast, moving toward central Florida, and in the Gulf is advancing arctic air across these regions."

Meanwhile, the upper level system hangs back in the Mississippi Valley and is pulling warm, moist air over the frigid, arctic airmass.

"This set up is classic for widespread freezing rain and sleet. Reports of freezing rain and sleet have been on-going mostly along the coast, with light to moderate snow further inland.

"This wintry mix will continue through Tuesday night for the Gulf Coast states along with the snow in the deep South."

In Florida, more than 80 flights were canceled at the international airports of Miami and Fort Lauderdale-Hollywood. Nationally a total of 3,000 flights were scrapped.

North Carolina, South Carolina, Georgia and some of Florida would be hit with more unusually cold weather on Wednesday, forecasters say, warning of snow north and west of there.

The cold front over Florida is expected to give way on Thursday to showers. (AFP)

SOURCE: AFP