Mrs. Claus better pack an extra thermos of hot chocolate in the sleigh this year, as poor Santa is in for a frigid ride through Western Pennsylvania on Christmas Eve.

The National Weather Service is predicting a wind chill factor of minus 13 degrees for Christmas Eve night and Christmas morning.

Myranda Fullerton, a meteorologist with the National Weather Service in Pittsburgh, said a very strong arctic cold front will hit the Pacific Northwest, cross the plain states and enter the Ohio Valley on Christmas Eve.

“With that, you’re going to see rain on the 23rd quickly changing over to snow in the afternoon and evening,” Fullerton said.

The arctic air will then arrive, which could make the final trip home from work before the holiday a little dicey.

“During rush hour on the 23rd, there could be some icy conditions even though you’re not getting snow yet,” Fullerton said.

On the 24th and 25th, cold, blustery snow showers could put down 1.5 to 2 inches of snow, she said.

“It’s hard to tell the accumulation yet,” Fullerton said. “We’re not looking for an extreme accumulation event, but anything that does fall, because it will be so cold, will have a tendency to stick on the roads and bridge overpasses.”

She said the daytime high on Christmas Eve will be 16 degrees, with a low of 3 degrees overnight and into Christmas morning.

Blustery winds will join in the mix due to a low pressure system working its way across Western Pennsylvania.

“Even though you’ve got low temperatures in the single digits, when you factor in the wind, we anticipate negative wind chill values,” Fullerton said.

The coldest Christmas Eve on record in the Pittsburgh area was in 1983, when the mercury dipped to 13 degrees.

“So this system has the potential to break records,” she said.

The coldest Christmas Day also was in 1983, when a low temperature of zero was recorded.

“It could be a top-10 coldest Christmas,” Fullerton said.

She said National Weather Service meteorologists look at data from multiple weather models and pull out the average to predict weather conditions.

“As we get within 72 hours of Christmas Eve, we’ll have more accurate accumulation totals,” Fullerton said.

She cautioned revelers against leaving any pets outdoors when the temperatures dip, and advises travelers to wear several layers of clothing and take blankets and a first-aid kit with them if they travel by car.

Fullerton also advises motorists to be aware of the weather along their route, as snow accumulations in the Appalachian Mountain ridges can be much higher than in the lowlands.

“Look ahead to where you are going,” she said. “Conditions can be worse the farther east you travel in Pennsylvania.”

Christina Gibbs, spokeswoman at state Department of Transportation’s District 10, said it’s still very early to know exactly what weather we’re going to get at the holiday or the timing of any snow.

“I anticipate having a statewide weather meeting later this week once the meteorologists have a more solid understanding of the anticipated storm,” Gibbs said. “I’ll know more about our specific plans once we hear the latest weather reports.”

She said Butler County crews are operating on shifts with 24-hour coverage and trucks and supplies are all in good status.

“So once we know what type of precipitation we’ll be getting, the temperatures and the timing of the storm, we will make the call as to the type of roadway treatment that will work the best under the conditions,” Gibbs said.

While planning a subarctic-feeling trip to Christmas dinner, motorists should consider the effect low temperatures have on their vehicles.

Ray Shafer, service adviser at Butler Tires for Less, said there are steps motorists can take to ensure their gift-filled truck, car or SUV will make it to its Christmastime destination.

Shafer said that, first, motorists should have their battery checked at a service facility to ensure its cold-cranking amps are sufficient.

“The cells inside the battery can be depleted if it’s too cold,” he explained.

Motorists also should check their antifreeze level to ensure the reservoir is full, and make sure the antifreeze inside is rated to protect to minus 35 degrees.

The correct tire pressure also is key in any weather, Shafer said.

Drivers of a certain age will recall fuel-line freeze up warnings in years past, but Shafer said that problem has been negated by the additives gasoline companies add in the winter to prevent the problem.

Shafer said he hopes everyone traveling for the holidays has a safe trip and a happy time with relatives and friends.

“Just be careful with the weather and dress warm,” he said.