As wind chills plummet to dangerous levels, the decision to close schools becomes critical.Kevin Wagner, a lead meteorologist with the National Weather Service in Milwaukee-Sullivan, explained the process behind these decisions.Were expecting wind chills of 30 to 35 below zero tonight into tomorrow, Wagner said. Thats the threshold we consider dangerous. Frostbite can occur in just 15 to 30 minutes. An Extreme Cold Warning goes into effect overnight for all of Southeast Wisconsin.When warnings are issued, Wagners team regularly updates schools through early-morning webinars and emails to share the latest data.For this warning, we had a webinar at 3:45 a.m. specifically for schools, Wagner said. We aim to get the most accurate information to decision-makers so they can act quickly to keep people safe.Watch: Meteorologist explains how schools decide to close amid freezing temperatures Local Meteorologist discusses factors in school closure decisions amid freezing temperaturesMilwaukee Public Schools, the largest school district in Wisconsin, will be closed Tuesday. Many other districts followed suit.Parents like Sherie Erving and Sylvester Rogers, who were watching their son play basketball at MSOEs Kern Center, learned about the closure during the game.Its definitely warm in here, but brisk outside. They get a second day off because of the weather as well, Erving said. Her son goes to Messmer High School in Milwaukee. While safety is the priority, the decision to close schools sparked mixed reactions.Rain, sleet, snowwe had to get out there when I was a kid, Erving joked. They give kids a little more leeway these days.Students, however, were thrilled with the unexpected break.I hear its supposed to be negative degrees outside, said Chantel Ringo, a senior at Messmer. I dont want to go out there, so I hope they close schools.