Several buildings can be seen damaged on the southside of Neola, Iowa on Thursday, Dec. 16, 2021. A storm brought tornadoes and strong winds to the area on Wednesday night. (Chris Machian/Omaha World-Herald via AP)

OMAHA, Neb. — At least five people died as a powerful and extremely unusual storm system swept across the Great Plains and Midwest amid unseasonably warm temperatures, spawning hurricane-force winds and possible tornadoes in Nebraska, Iowa and Minnesota.

In southeastern Minnesota, Olmsted County Sheriff's Lt. Lee Rossman said a 65-year-old man was killed Wednesday night when a 40-foot tree blew onto him outside his home. In southwestern Kansas, blinding dust kicked up by the storms Wednesday led to two separate crashes that killed three people, Kansas Highway Patrol trooper Mike Racy said. And in eastern Iowa, a semitrailer was struck by high winds and rolled onto its side Wednesday evening, killing the driver, the Iowa State Patrol confirmed.

The storm shifted north of the Great Lakes into Canada on Thursday. More than 400,000 homes and businesses were without electricity in Michigan, Wisconsin, Iowa and Kansas, according to poweroutage.us, which tracks utility reports.

The destructive weather system developed amid unprecedented warmth for December in the Plains and northern states. That included temperatures that rose to 70 degrees Fahrenheit across southwestern Wisconsin on Wednesday evening. The Weather Company historian Chris Burt compared the heat to that of a “warm July evening.”

“I can say with some confidence that this event (the heat and tornadoes) is among the most (if not THE most) anomalous weather event ever on record for the Upper Midwest,” Burt wrote in a Facebook post.