Temperatures across the western half of the nation are dropping by as much as 40 degrees below normal as an Arctic cold-air mass moves south.
A storm system that brought up to 2 feet of snow and bitter cold to the Rockies and Northern Plains was moving south Tuesday.
The cold air was expected to threaten citrus crops in California and move into Texas by the end of the week.
AccuWeather meteorologist Tom Kines says a very southerly jet stream is driving down temperatures 20 to 40 degrees below normal.
In Wyoming, snow and ice closed a stretch of Interstate 90 between Sheridan and Buffalo Tuesday morning and temporarily halted flights at Jackson Hole's airport.
Officials issued travel advisories and warned people to protect themselves against frostbite.