Temperatures are expected to plummet over the weekend, bringing life-threatening conditions to large stretches of the United States. The polar vortex will send temperatures below freezing for much of the country starting this weekend and stretching into next week,

Erin Davis/Axios Visuals An invasion of frigid air from the Arctic is sweeping south from the Plains and Ohio Valley Sunday, moving towards the Southeast and East. Threat level: The colder-than-average temperatures threatens public health for those exposed to the wind and cold,