A blast of dangerously cold weather prompted the closing of many school districts Wednesday, as education officials statewide wrestled with how best to protect students from the coldest weather of the year.

"If you look at what the experts are saying with windchill and cold temperature, it can be less than 10 minutes before our students have frostbite," Minneapolis public schools spokesman Stan Alleyne said of the district's decision to close for the day. "We don't want to put our students in that situation."

Once Minneapolis school officials made their decision, leaders in Anoka-Hennepin, the state's largest district, soon followed, citing the extreme cold and "the safety of our students and staff." Many other suburban districts followed suit and told the kids to stay home. Benilde-St. Margaret's in St. Louis Park opted for online-only instruction Wednesday.

St. Paul public schools and some suburban school districts remained open or delayed the start of classes by a couple of hours. St. Paul officials said they are leaving the decision up to parents, and are excusing absences for students who stay home.

Windchills across the state shortly before sunrise Wednesday reached well into the 30s below zero and even 40-plus below in some northern communities, according to the National Weather Service.

In the Twin Cities area, air-temperature lows were in the upper single digits below zero, with windchills in the upper 20s to lower 30s below zero, the NWS said. The airport in the North Shore town of Grand Marais was the state's cold spot, reporting an actual temperature of minus-24 at 7 a.m., with a windchill of 54 below.

Some school officials are facing their first big test of new policy changes that set guidelines for closings due to cold and snow.

St. Paul schools remained open because windchill temperatures failed to hit the minus-40-degree mark the district set for winter closings, said district spokeswoman Toya Stewart Downey.

This past fall, district officials established a threshold for closings because "last year we closed for six days, and it was always pretty ambiguous whether we were going to close or not," she said. "We thought it would be easier to set a threshold and let that be the guide for our families and our staff."

Stewart Downey said they were trying to do what is best for their students and their district. "For many students, school is the safest place they can be on a cold-weather day. We have free breakfast for all students, and they're guaranteed lunch and a safe place with adults who can be there for them," she said.

Parents agree, disagree

Stewart Downey doesn't expect all parents to agree with the district remaining open.

"It's always a mixed bag," she said. "You get people who say we should stay open when we close and get those who say we should close when we stay open."

Minneapolis took a different approach, citing the demographics of students in the district.

Those kind of extreme temperatures pose too much of a risk for students, particularly those without transportation to school, leaders in Minneapolis said.

"We have a lot more walkers than some of the suburban districts," said Alleyne, with Minneapolis schools. "We are looking out for the safety of our students." Several students took to social media late Tuesday pleading with Gov. Mark Dayton to close schools for the day. Last year, Dayton took the unusual step of canceling classes statewide on Jan. 6 after temperatures fell to minus 22, with windchills dipping to 48 below in the Twin Cities.

Dayton spokesman Matt Swenson said late Tuesday that the governor was leaving the decision up to school district leaders.

Decisions elsewhere

School officials in Austin and Winona in the southeast corner of Minnesota got ahead of the game, deciding by early Tuesday afternoon to start classes two hours late Wednesday. St. Thomas Academy in Mendota Heights soon joined the two-hour-late approach for Wednesday morning, as well.

A windchill warning from the National Weather Service kicked in at 2 a.m. Wednesday and was expected to last late into the morning, forecasting what the agency describes as "dangerously cold windchills across all of central and southern Minnesota and into western Wisconsin."

Thursday and Friday's weather will continue to be bitterly cold. Thursday's high could hit 13 degrees, but it will drop back to single digits on Friday, with windchills below zero each day, but probably not extreme enough to trigger school closings in Minneapolis or St. Paul.

Star Tribune staff writers Alejandra Matos and Mary Lynn Smith contributed to this report.

Kim McGuire • 612-673-4469