BISMARCK, N.D. (AP) -- With the wind chill falling to almost minus 40, Steve Hendershot's mind was elsewhere Thursday as he and his crew of roustabouts worked an oil rig in North Dakota's booming oil patch. On palm trees and beaches, in fact. "Sometimes you just got to close your eyes and dream of a warm, happy place," said Hendershot, working near Souris. "I'm doing that today." The cold weather sweeping the Plains wasn't cooling off work in the oil patch, which moves forward in all kinds of weather. But even hardened oilmen were taking note of the dangerous conditions that were expected to keep daily highs below zero until Sunday. A powerful winter storm that slammed much of the nation kept intensifying Thursday, draping many communities in skin-stinging cold. The system dumped 1 to 2 feet of snow in parts of Minnesota and Wisconsin, forcing school closures and temporary power outages and delighting skiers who hit the slopes despite temperatures in the single digits. The south-central U.S. braced for the next blow, expected to come Friday in the form of sleet and ice that could imperil millions unaccustomed to the treacherous combination of moisture and bitter cold. In Montana, temperatures fell as low as minus 26 in Great Falls and minus 27 in Havre, both records. In parts of the Rockies and Northern Plains, wind made those conditions feel even colder. The deep freeze, blamed on the jet stream's move southward, was expected to linger at least through the weekend. With the mercury falls this low, the cold inflicts pain on exposed skin almost instantly, and water poured from a cup can freeze before hitting the ground. Contact lenses begin sticking to eyeballs. Cars fail to start, and people begin longing for heavy foods. Pets refuse to go outside. The Red Cross urged people to stay inside or layer up to guard against frostbite if they must go out. The agency also asked residents to check on neighbors, especially those who need special assistance or live alone. Holiday events were called off. In Rapid City, S.D., officials concluded it was too cold for ice skating. Oil patch workers endure by layering up beneath fire-retardant clothing and taking breaks in small heated shacks called "doghouses," which are often near rigs. Many companies also try to hire locals with at least five years of experience. "If they've made it that long, they're probably going to stick around," said Larry Dokken, a veteran oilman whose consulting firm recruits workers for oil companies. Hendershot has shared the advice of dreaming of warmer climes to fellow workers in years past. He said a few have taken it literally. "Some have actually left and gone to that warm, happy place," he said. Some workers gripe about the bone-numbing temperatures, he added. Many others take pride in withstanding it. "This is what I love to do," said Craig Hovet, during a break from maintenance work on a well Wednesday near Mandaree. "The joke around here is: This kind of weather keeps out the riffraff."