Big chill: Why us? Why now?

The big chill that has enveloped Minnesota, closed schools and overwhelmed auto services is bringing the coldest temperatures to the state in almost two decades.

The source is a "big chunk of air mass that has broken off" from an area near the North Pole and the Northwest Territories of Canada, said National Weather Service meteorologist Jim Taggart, and it has moved into Minnesota virtually unchanged.

"In past years when we may not have had as much snow, the Canadian air gets a little warmer as it reaches Minnesota, and the cold is not as pronounced," Taggart said. But this year there's plenty of snow everywhere.

"The reason why it's so cold is there's not a lot of modification as the air mass comes down," he said.

Making things worse, Taggart said, are winds of 10 to 15 miles per hour.

"On a normal day that's not much, but when you have temperatures of 25 to 30 below zero, that makes the windchill values near minus 60." Exposed skin will freeze in five minutes in those conditions, he said.

"This is probably going to be one of those days where you really don't want to be outside unless you have to," Taggart said.

The coldest temperature ever recorded in the Twin Cities was 41 below on Jan. 21, 1888, Boulay said, and the coldest high on record for the metro was 20 below on Jan. 15, 1888. But that doesn't mean coping with the frigid conditions will be easy, Boulay said.

"There's a whole fleet of cars on Twin Cities roads that haven't seen minus 25," he said. "The last time was Dec. 26, 1996, when we got to minus 27 at the airport."

Super-cold air can also cause underground problems for septic systems and other pipes in locations where the ground freezes deeper than usual.

Dan Olson, public information officer for the Minnesota Pollution Control Agency, said there have been few reports of frozen septic systems so far. "Our assumption is the cold temps are not causing a lot of septic problems due to the fact that most all of Minnesota has some snow cover, which provides insulation," he said.

The high potential for frostbite and more serious problems has created an avalanche of cancellations, from schools and church events to classes and meetings.

Officials said Three Rivers park centers will remain open with normal hours, but some public programs may be modified if necessary because of the extreme cold.