At least 11 people died and dozens were injured in tornadoes that swept through the Dallas area and caused substantial damage while six people have died in flooding in the US mid-west.
It was the latest in a succession of powerful weather events across the country - from heavy snow in New Mexico, west Texas and the Oklahoma Panhandle - to flash flooding in parts of the plains and mid-west.
Days of tumultuous weather have led to 36 deaths overall - those in Texas, plus five in Illinois, one in Missouri and 19 in the south east.
The full extent of damage along a nearly 40-mile stretch near Dallas was becoming clear on Sunday - houses destroyed, vehicles mangled, power lines down and trees toppled. Heavy rain and wind hampered clean-up efforts.
"This is a huge impact on our community and we're all suffering," Garland police spokesman Pedro Barineau said of the community about 20 miles north east of Dallas, where eight people died, 15 were injured and about 600 structures, mostly single-family homes, were damaged.
The weather service said an EF-4 tornado, which is the second-most powerful with winds up to more than 200mph, hit the community. At least three people who died were found in vehicles, said Nr Barineau.
The destruction in Garland was so overwhelming that Dallas County Judge Clay Jenkins declared the city a disaster within mere minutes of seeing the toll firsthand.
"I don't declare local disasters lightly," Mr Jenkins said. "But I looked at the scene for 10 minutes, spoke to the incident commander and then called the lawyers to bring the paperwork."
In the nearby town of Rowlett, city manager Brian Funderburk said Sunda that 23 people were injured, but that there were no deaths and no reports of missing people. The weather service said damage indicated it was likely an EF-3 tornado, which has winds up to 165mph.
Three other people died in Collin County, about 45 miles north east of Dallas, according to sheriff's deputy Chris Havey, although the circumstances were not immediately clear.
National Weather Service meteorologist Matt Bishop in the Fort Worth office said the tornado outbreak at this time of the year for North Texas occurs "from time to time ... but it's certainly not something that happens regularly."
On the other side of the state, a snowstorm was accompanied by plunging temperatures. The Texas Department of Public Safety in Amarillo strongly discouraged travel throughout the entire Texas Panhandle - a 26-county area covering nearly 26,000 square miles - because blowing and drifting snow had made the roads impassable. Interstate 40 west of Amarillo to the New Mexico border will be closed until Monday morning.
Meanwhile, Oklahoma governor Mary Fallin declared a state of emergency as there were blizzard conditions and an ice storm warning out west and flood warnings in the east, where one community had received 9 inches of rain.
Further north, rain caused dangerous driving conditions and flooding in Missouri and Illinois. A part of Interstate 70 was closed near St Louis because of water over the road, and KYTV reported that authorities recovered the body of a driver from a creek in the south west part of the state on Saturday.
Three adults and two children drowned in southern Illinois when the vehicle they were in was swept away and sank in a rain-swollen creek.
The death toll in the south east linked to severe weather rose to 19 when Alabama authorities found the body of a 22-year-old man whose vehicle was swept away while attempting to cross a bridge. Ten people have died in Mississippi, and six died in Tennessee. One person was killed in Arkansas.