Just as everyone begins to accept and prepare for subzero wind chills and frozen pipes, the goofy winter weather of Western Pennsylvania will go back above normal.

With the temperature having dipped to 2 degrees at about 3:30 a.m. yesterday, the high today is expected to reach 32, and by tomorrow, Pittsburgh will see a high around 50, said Brad Rehak, a meteorologist with the National Weather Service.

"That's kind of just the way things are," he said. "It's not unusual."

The normals around this time of year, Mr. Rehak said, are 38 degrees for a high and 24 for a low.

The last time the area was as cold as 2 degrees was on Feb. 15, 2007. The cold air yesterday was caused by an Arctic front coming from the northern Plains, Mr. Rehak said.

He expected temperatures last evening to drop to about 8 degrees before gradually warming overnight.

Because of the frigid temperatures yesterday, many schools in the area had delays or closings.

Pittsburgh Public Schools originally called for a two-hour delay on Sunday evening, but they changed it to a cancellation at 6:30 a.m., said spokeswoman Ebony Pugh.

The change was prompted both by the cold and problems the district was having with its buses.

"The buses did play a factor," Ms. Pugh said. "It was mostly about the kids being out there in the extreme cold."

Typically, the district will call for a delay when temperatures are predicted to be 10 or below, based on worries about children not being dressed warmly enough and the potential for frostbite.

"We get concerned about having kids standing outside," she said.

The cold made for a hot business day for plumbers.

Joe Benz, general manager for Gillece Plumbing and Heating in Bethel Park, said his company got more than a half-dozen calls for frozen pipes yesterday. Before workers could get to the houses, most of them called back to say the pipes had thawed by themselves.

Whether pipes will freeze depends not only on the temperature, Mr. Benz said, but how windy it is.

Most pipes are well-protected down to 10 degrees, he said. When high winds gust across them, they're much more likely to freeze.

That shouldn't be a problem again for at least the next several days.

Though some snow is expected tonight, it will change to a wintry mix and then rain by Wednesday.

Thursday is expected to be dry, and the high about 42 degrees.

"Just as usual, we have snow when we don't want it, and for Christmas, it's brown and gray," Mr. Rehak said.