Lindsey Thompson's first day at her new job at a computer software company was Jan. 6, the day Gov. Mark Dayton ordered all Minnesota schools to close because of the extreme cold. Her parents cared for her three children that day so she could start work.

But Tuesday -- the fifth day this month that most Twin Cities-area schools have closed because of dangerously cold weather -- the grandparents were unavailable, and Thompson was among thousands of Minnesota parents who had to juggle work and child care.

"I still love winter," said Thompson, who lives in Woodbury and works in Minneapolis. "But this is ridiculous."

With wind-chill temperatures expected to be as low as minus 50 degrees early Tuesday, schools in St.

Paul, Minneapolis and elsewhere are closed again after calling off classes Monday. The University of Minnesota's Twin Cities campus has canceled Tuesday morning classes; classes resume at noon.

After 10 years at home raising kids, Thompson had just started working again when the first canceled school day was announced. Her children are in first and fourth grade at Liberty Ridge Elementary in Woodbury; a 4-year-old is in a child care program that also has closed. She and her husband each have been working half days at home.

"Fortunately, my employer is flexible," she said, "but it's just very challenging to take conference calls while I have three children home."

A decision to cancel school is challenging for administrators, too. Although Dayton's move set a precedent, school-closure decisions since then have been made by individual districts. Several district leaders said they set the threshold at minus 20-degree air temperature and minus 40-degree wind chills as a guideline.

In a message to parents, Superintendent Jane Berenz of Rosemount-Apple Valley-Eagan schools said she was concerned about the lost time in class and inconvenience to families, but student safety was her top priority.

"We want students to be at school learning, whenever we feel we can get them there safely," Berenz wrote. "In the unusually cold temperatures we have been experiencing, buses are more prone to breakdowns and delays, and children with exposed skin can be frostbitten in as little as five to 10 minutes."

Multiple school closures are unlikely most winters. The loss of five school days in one month is unprecedented, and many districts are planning to change the school calendar to make up the lost time.

Toya Stewart Downey, St. Paul Public Schools spokeswoman, said neither she nor her colleagues with more than two decades with the district could remember such a string of weather closures.

The unexpected days off also have been challenging for parents who don't have to scramble for day care.

"Just because I'm not working doesn't mean this isn't a huge disruption," said Jill Driscoll, who has children in St. Paul public schools in second, fifth and seventh grades. "There are things I need to get done and when suddenly you don't have school again, it throws everybody into disarray."

"The first winter day when school was canceled, we all lounged around. But by Day 4 of this, we're kind of overstaying in our pajamas and watching a movie and snacking all day.

"I understand the argument that it's dangerously cold, but I think that's only one factor," Driscoll said. "A lot of kids rely on our schools for breakfast and lunch, and they're not getting it. There are kids being left unsupervised at home. Just because you close school doesn't mean you are automatically keeping kids safe. I admit it's a complicated issue, but for me personally, I've landed on keep schools open."

The lost days mean several school districts will have to make up the time.

Minnesota requires students be in school a certain number of hours, based on their grade. Most districts schedule more than the state minimum, but losing five instruction days has district leaders looking to add time to the calendar.

For instance, Lakeville school board members are considering converting Presidents Day, which is scheduled as an off day for students, into a make up day. Mounds View school leaders may add time in June.

Christopher Magan, Molly Guthrey and Andy Rathbun contributed to this report.