The dangerously cold weather was still setting low-temperature records in many Iowa communities Thursday morning. It was minus 30 in Cedar Rapids, shattering previous record -21 set Jan. 31, 1996. The low of -28 in Iowa City was 10 degrees colder than the previous record of -18 set Jan. 31, 1996. New lows for the date also were set in Dubuque and Waterloo. The bitter cold chilling the middle of the U.S. also broke records in several Iowa cities Wednesday, including Des Moines.

A meteorologist says parts of the northern U.S. are going to experience an “unprecedented” and “dramatic warm-up.” Weather Underground’s meteorology director Jeff Masters says places in Michigan and Illinois experiencing record or near-record cold this week are expected to be around 50 degrees Fahrenheit by Monday. He said Thursday that he hasn’t before seen a 70-degree shift in temperature during the winter. He says “past record-cold waves have not dissipated this quickly” and that the region seems headed for “spring-like temperatures.”

Masters says the polar vortex is “rotating up into Canada” and is not expected to return in the next couple of weeks. He says it might return in late February, but if it does, “it won’t be as intense.”