Subzero temperatures predicted next week could force suburban school districts to cancel classes just as students are scheduled to return from winter break.
Administrators are anxiously monitoring weather forecasts, even though some say severe cold alone doesn't automatically warrant school closings.
Typically, districts build in allowances for multiple "snow days" into the school calendar. Yet there is no statewide consensus on how cold is too cold for children to be in school.
"There is no threshold temperature," said Patrick Mogge, spokesman for Elgin Area School District U-46. "We're going to continue to monitor. It is rare to close schools due to low temperatures, and that decision would not be made this far ahead based on a forecast."
Temperatures are expected to hover between minus 5 and minus 11 degrees on Monday, though in some places it could dip to 20 below zero.
U-46's emergency procedures cite numerous factors that determine closings, including condition of roads, parking lots, sidewalks and walking paths, severe windchill factor, heavy overnight snowfall, and whether building emergency exits and air handling systems are blocked.
Busing roughly 26,000 students -- more than half U-46's student population -- may pose problems if heavy snowfall continues. Monday, though, is an "institute day" for teachers to work on lesson planning before classes resume Tuesday, Mogge said.
Forecasts of wind chills reaching minus 45 on Tuesday morning are worrisome, said Gurnee School District 56 Superintendent John Hutton.
"It's kind of right on that borderline," Hutton said. "It's something I'm going to keep track of over the weekend. When you start getting close to negative 20, it's getting pretty cold."
Lake County received some of the heaviest snowfall in the suburbs, and Hutton said he is concerned about the cumulative effect of the snow and severe low temperatures.
"It's going to make the stops more difficult to pick the children up," he said. "Both of them together is going to make a very challenging couple of days for us."
Closing schools for a day also is not an easy decision as it puts many parents in the difficult situation of trying to make last-minute day care arrangements, Hutton said.
Hutton recalled a similar wintry morning four years ago when the temperature was 20 below zero.
"I was trying to figure out a way to have school that day," Hutton said, but he added that his wife reminded him that it was too cold for children to be outdoors and he canceled classes immediately. "Student safety and making sure the kids are OK is our main priority," he said.
At Naperville Unit School District 203, officials are planning to start running buses earlier to ensure they are warmed up and ready for students, and the maintenance staff will be monitoring building heating systems, spokeswoman Susan Rice said.
"On days when it is extremely cold, students are welcomed into the building upon their arrival and have recess indoors," she said. "It's important that students prepare for the extreme cold weather by dressing appropriately with plenty of layers. Students who walk to school may require a ride to reduce their exposure time to the cold."
Barrington Unit District 220 spokesman Jeff Arnett said it's unlikely any decision about canceling school would be made earlier than the night before due to the possibility of the forecast changing.
The district has canceled classes before due to the cold -- specifically the wind chill-- out of concern for young children walking to school. But such cancellations are rare.