A monster storm has swept across the United States, triggering tornadoes, wildfires and dust storms and killing at least 19 people.

Most of the fatalities occurred in Missouri from an outbreak of several tornadoes that flipped semi-trailers and demolished homes, claiming 11 lives.

The extreme weather system also fuelled 100 wildfires in central US, and caused fatal car accidents in Texas from blinding dust storms.

The massive storm system moved across southern and central US, impacting numerous states including Missouri, Oklahoma, Arkansas, Texas, Tennessee, Illinois and Mississippi.

More extreme weather conditions — including hurricane-force winds — are forecast to affect an area home to more than 100 million people.

Winds gusting up to 130 km/h were predicted from the Canadian border to Texas, threatening blizzard conditions in colder northern areas and wildfire risk in warmer, drier areas to the south.

“Numerous significant tornadoes, some of which should be long-track and potentially violent, are expected this afternoon and evening,” the National Weather Service said Saturday.

Coroner Jim Akers of Butler County, Missouri, said one person was killed early Saturday (local time) after a tornado ripped apart a home roughly 177 kilometres east of Bakersfield.

“It was unrecognizable to be a home. Just a debris field,” Akers said, describing the scene that confronted rescuers when they arrived.

“The floor was upside down. We were walking on walls.”

Three people were killed Friday (local time) in car crashes during a dust storm in Amarillo County in the Texas Panhandle, according to Sergeant Cindy Barkley.

One pile-up involved an estimated 38 cars.

“It’s the worst I’ve ever seen,” Barkley said, calling the near-zero visibility a nightmare.

“We couldn’t tell that they were all together until the dust kind of settled.”

Wildfires have broken out in Oklahoma. Photo: AAP

Evacuations were ordered in some Oklahoma communities as more than 130 fires were reported across the state.

The State Patrol said winds were so strong that they toppled several large trucks.

“This is terrible out here,” said Charles Daniel, a truck driver hauling 14.6-metre trailer along Interstate 40 in western Oklahoma.

“There’s a lot of sand and dirt in the air. I’m not pushing it over 55 mph. (88 km/h) I’m scared it will blow over if I do.”

Forecasters said the severe storm threat would continue into the weekend with a high chance of tornadoes and damaging winds on Saturday (local time) in Mississippi and Alabama.

Heavy rain could bring flash flooding to some parts of the East Coast on Sunday (local time).

Homes are left in ruins after a tornado in Missouri. Photo: AAP

Experts say it’s not unusual to see such weather extremes in March.

“What’s unique about this one is its large size and intensity,” said Bill Bunting of the National Weather Service’s Storm Prediction Centre in Norman, Oklahoma.

“And so what that is doing is producing really substantial impacts over a very large area.”

The weather service said at least five tornadoes were reported in Missouri on Friday (local time), including one in the Saint Louis area. Several buildings were damaged.

The Storm Prediction Centre said fast-moving storms could spawn twisters and hail as large as baseballs, but the greatest threat would come from straight-line winds near or exceeding hurricane force, with gusts of 160 km/h possible.

The Storm Prediction Centre said parts of Mississippi including Jackson and Hattiesburg and areas of Alabama including Birmingham and Tuscaloosa would be at a high risk.

Severe storms and tornadoes were also possible across eastern Louisiana, western Georgia, central Tennessee and the western Florida Panhandle.

Storm chasers capture footage of a tornado. Photo: X

Wildfires in the Southern Plains threatened to spread rapidly amid warm, dry weather and strong winds, and evacuations were ordered Friday for some communities in Texas, Oklahoma, Kansas, Missouri and New Mexico.

High winds also knocked out power to more than 300,000 homes and businesses in Texas, Oklahoma, Arkansas, Missouri, Illinois and Indiana.