Killer tornadoes in the U.S. Southeast and subzero cold stretching as far as Texas were on Tuesday blamed for seven deaths and massive power outages that cancelled COVID-19 inoculations, Reuters reports.

Forecasters said the weather will maintain its grip on many parts of the United States through to Friday, with up to four inches of snow and freezing rain expected from the southern Plains into the Northeast.

"We're calling it Storm System No. 2, with very similar placement to the previous storm," Reuters quotes meteorologist Lara Pagano of the National Weather Service's Weather Prediction Center in College Park, Maryland.

In Lincoln, Nebraska, a reading of minus 31 degrees Fahrenheit (minus 35 degrees Celsius) on Tuesday shattered a record set in 1978 of minus 18F (minus 27C).

In typically toasty Dallas-Fort Worth, minus 1F (minus 17C) broke a record set in 1903 of 12F (minus 11C).

"That's what people are waking up to this morning: It's just dangerous," Pagano said.