( CNN ) For much of the U.S. , stepping into a walk-in freezer will be a lot more comfortable than going outside . From Minnesota to Texas , another blast of frigid weather is walloping the country . Here 's what to expect : . Wind chills will plunge to about minus 40 Sunday in parts of North Dakota and Minnesota as another Arctic blast barrels through , CNN meteorologist Derek Van Dam said . As the work week starts , other cities will endure the mind-numbing freeze . Chicago 's wind chill will be 20 below zero on Monday . And on Tuesday morning , Boston will suffer a wind chill of minus 20 , while New York and Philadelphia will grapple with wind chills of minus 4 . You know it 's bad when parts of Texas will be covered with ice . Up to 2 inches of sleet will fall in the Dallas-Fort Worth area Sunday and Monday , the National Weather Service office in Fort Worth said . In Kentucky , the massive weight of snow on the roof of a Walmart may have been enough to crack the walls . The store in South Williamson was evacuated and closed indefinitely after store employees detected the cracks , apparently caused by the load of snow on the roof , Walmart spokeswoman Tricia Moriarty said Saturday . And the roof slid off the top of a home in Concord , New Hampshire , CNN affiliate WMUR reported , leaving nothing to protect the family from relentless snow . It 's not clear exactly what caused the roof to slide off , WMUR said , but state officials are warning about the dangers of roof collapses amid heavy snowfall . At least 26 people have already died from weather-related incidents in the U.S. and Canada over the past week . The Tennessee Emergency Management Agency reported 21 deaths , including 11 from hypothermia and several from vehicle accidents . A dialysis patient who was unable to get treatment also died . In Boston , a man died after suffering a heart attack while shoveling snow , Mayor Martin Walsh said . In North Carolina , a 19-year-old woman died in a weather-related traffic crash , the governor said . In New Hampshire , a woman died apparently from exposure to the cold in an area known for hiking , state officials said . And in Toronto , police said 3-year-old Elijah Marsh died after wandering out of an apartment on his own wearing only a T-shirt and boots . Thousands of air travelers will be grounded across the country Sunday . More than 600 flights into , out of or within the U.S. have been canceled , according to flightaware.com . Airports in Denver , Philadelphia and New York are the most affected . While the Northeast will stay frigid the next few days , the snow and freezing rain will ease up by midday Monday . And the massive snowfall in the Denver area could be a boon for outdoor athletes , CNN meteorologist Ivan Cabrera said . `` In the higher elevations , we 're going to be measuring in feet -- excellent news if you are out skiing in Colorado . '' CNN 's Joe Sutton , Christine Sever , Ralph Ellis and Vivian Kuo contributed to this report .
Even Dallas can get 2 inches of sleet . About a dozen hypothermia - related deaths have been reported in the past decade .