Chaotic weather, from surprising heat in California to the threat of storms rolling into the East Coast, has put over half the US population in the path of extreme conditions.
More than 200 million people or some 58 per cent of the population, were under a weather alert on Monday, according to the National Weather Service and storms across the nation's eastern half forced airlines to cancel more than 4500 flights, according to the online portal FlightAware.
Many schools closed early in the mid-Atlantic states, where high winds were in the forecast.
Blizzards buried parts of Michigan, Wisconsin and Minnesota while torrential rains flooded homes and washed out roads in Hawaii.
Airport delays and cancellations piled up in some of the nation's largest airports - including those in New York, Chicago and Atlanta.
The private weather service AccuWeather warned about extreme heat and wildfire advisories to flood and freeze watches from the National Weather Service.
The storm system that dropped snow in the Midwest barrelled toward the East Coast with the potential for high winds and tornadoes, the weather service warned.
"Wind is the primary threat, but within any of these areas of strong wind there could be some embedded tornadoes," said Evan Bentley, a meteorologist with the weather service.
The biggest threat stretched from Maryland to the upper edge of South Carolina.
In New York City, four people, including a child, died Monday afternoon after a fire in a three-story apartment building spread during heavy winds.
Blizzard conditions continued in the Upper Midwest and Great Lakes after the storm walloped parts of Wisconsin and Michigan with metres of snow.
Since Saturday, nearly 61cm had fallen in the northern Wisconsin town of Mountain.
Another round of snow and gusts on Monday could bring another 30cm of snow across Michigan's Upper Peninsula.
A heat dome over the Southwest will push temperatures well into the triple digits in Arizona most of the week, much earlier than normal.
California is starting to feel like summer too. The San Francisco Bay Area and Sacramento will see temperatures pushing towards 32C by midweek.
While temperatures are expected to reach 38C, the threat of wildfires around Los Angeles is relatively low because winds will be light.
Dry and windy conditions were charging the largest wildfire in Nebraska's history. Three fires in the state have consumed more than 3000sq/km of mostly grassland.
Unrelenting rains triggered landslides, washed away roads and flooded homes and farmland in Hawaii over the weekend.
All of Hawaii's islands had spots with more than 38cm of rain while parts of Maui were overwhelmed with double that amount, the weather service said.
While the worst of the storm has passed, more heavy rain is expected later this week.