t. peonalnformaon. ightly news" begins right now. >>nnou: om n ne world headquarters in new rk, this is "nbc nightly news" with lester ht. >>> good ening. ere are warnings tonighof a dangerous freeze about toll plunge a huge part of theountry in its grip. as t dreaded par vortex moves south, parts of stas ll see temperatu below nd ndillshat ke it feel a lot colder. yes, it's winter. supposed to be cold, but as we've come to ow cold snaps deadly, and in this case tens of milons of people are bracing for the biggest chill so far this ason. a momen al roker, but we begin wh nbc'ron mott in boston. >> reporr: 65 million ericans bundled up against the brutal cold as the ever psentol voex unleashes wier's harest bite yo fe. >> reporter:oday the snow ldrought aur tennessee and the caronacaing trouble for commuter stranded in new york ere coldeather likely contributed to rush hour. in pennsylvania, a broken water pipe left th home frosted over, and in ccago florists are taking extra care wittheir valeine's da delivees. flowers. if they are f