Throw another log on the fire tonight. Or maybe the whole cord.

The mercury's going to free fall well into negative numbers. How low?

“Minus 12 by 8 a.m. Tuesday,” said meteorologist John Darnley of the National Weather Service in Pittsburgh.

But with the strong winds, it's going to feel even colder.

“The low point for the wind chill will be minus 31 at 2 a.m. Tuesday,” Darnley said.

An arctic cold front that started invading Western Pennsylvania about morning commute time today is to blame for the frigid temperatures and wind chills.

The weather conditions this morning resulted in the closings of Butler, Slippery Rock, Karns City and Moniteau school districts, and two-hour delays for all Allegheny-Clarion Valley School District schools and for elementary schools in the Freeport School District.

Schools in the Mars, South Butler and Seneca Valley school districts operated on a regular schedule.

One of a number of parents to call the South Butler district office to complain about classes not being canceled was Karen Gigliotti of Jefferson Township.

“I regret putting my children on the bus,” Gigliotti said this morning about her sixth and ninth graders.

She said her 4-wheel-drive vehicle slid some while she drove her children to a bus stop.

She kept another of her children home from elementary school.

Gigliotti said that children on the bus texted their parents, “saying how scary the roads were,” she said.

She also had no sympathy for administrators.

“Their lack of concern for our children and their staff is ridiculous, she said.

The arctic front has moved in and will stay a while, Darnley said. He called this type of cold weather “rare” for Butler County and the surrounding area.

The coldest air is expected this evening through Tuesday afternoon.

At 5 p.m., the forecast calls for a temperature of 4 below zero. By midnight, it will be 6 below zero with a wind chill of minus 27.

The temperatures and wind chills are to bottom out about 8 a.m. Tuesday.

“Then we'll see a little warm up for Tuesday afternoon,” Darnley said.

That “warm up” will see the temperature hit one degree — that's above zero — about 5 p.m.

“By Wednesday,” Darnley said, “we're looking at a high of 11. By Thursday, it'll hit 27.”

Wind gusts, which hit 41 mph at Butler County Airport at 5 a.m. today, will kick in again after midnight tonight, reaching 15 mph, and remain for much of Tuesday morning.

Despite the weather woes, there's good news out there — believe it or not.

The half inch to one inch of snow that fell in Butler County is the last batch we'll see until next week at the earliest.

Moreover, a high-pressure system building off the coast will start to warm things up for real on Thursday, Darnley said.

Thursday is expected to be partly sunny with a high of 27 and a low in the upper teens.

By Saturday, the temperate will hit 33 and Super Bowl Sunday will really be super, weather wise.

“We're looking for a high of 38 with a 20 percent chance of rain,” Darnley said.