Next week is expected to bring the coldest temperatures in 20 years.

“The snow is inconvenient, but the cold is worse,” said Lee Hendricks, a meteorologist with the National Weather Service in Pittsburgh.

Monday will start with temperatures in the mid-20s, but they it will drop to 10 degrees in the afternoon. By Monday night, the temperature will be 10 below zero. The overnight low is predicted at 17 below zero.

People will wake up Tuesday morning to temperatures between minus 5 and zero degrees and a wind chill of 40 below zero.

The last time the high temperature was below zero was in January 1994, which Hendricks described as “a fairly rotten month.” On Jan. 19, 1994, the high was 3 below zero with a low of minus 22, making it the coldest day on record.

Tuesday night, it will be about 10 below zero. Wednesday, it will heat up to 10 to 15 degrees.

The outlook for the rest of the winter is supposed to be near normal. However, Hendricks said there is a possibility for the weather to behave like it did in December, with extreme fluctuations that average out to be normal.

“It could be pretty much anything,” Hendricks said.

School delays

Temperatures and/or wind chills below zero can often warrant a school delay or closure, but it's usually dependent on the specific situation rather than a guideline.

“If it's below zero, we're definitely considering delays or cancellations,” said Mike Strutt, superintendent of the Butler School District.

He said looking at wind chills makes a determination a little more complicated. While a windchill is usually listed on colder days, it doesn't mean there will be wind.

Also there are the 1,200 to 1,500 students in Butler who don't rely on district transportation to consider. Those students either walk or are taken to school by their parents.

South Butler and Karns City school districts follow similar guidelines.

“There's not an absolute, but if the temperature is zero or below, that will likely at least warrant a delay,” said Eric Ritzert, Karns City superintendent.

He added the temperature can vary a bit throughout the district, sometimes by 5 degrees or more.

“Anything considered in extreme cold, we would take into consideration,” said Jason Davidek, South Butler School District spokesman. “There's no trigger point, so to speak.”

Linda Andreassi, director of communications for the Seneca Valley School District, said district officials are aware of the impending cold temperatures, but she added it's too early to make any definitive decisions regarding scheduling.

“Dr. Vitale and her executive team, including the transportation director, are in constant communication during times like these,” Andreassi said. “As soon as any decisions are made regarding delays or closures, we'll immediately notify our families using the various communication methods we employ for such situations.”

George Svolos, superintendent of the Moniteau School District, said, “We would look at the overall situation. Safety is the main reason. We look at the air temperature, the wind chill and the precipitation.

“We closely monitor the weather before we make a decision. I communicate with Campbell Bus to make sure that the buses are OK.”

Svolos said there is not a set temperature when he would call off school or delay school opening.

For example, he would not decide as early as Sunday night to close on Tuesday.

Maintaining safe roads during extreme colds also brings its challenges.

Mars School District Superintendent Jim Budzilek said he talks with the bus garage, transportation director Jane Roth, and A.J. Myers and Sons busing company to determine whether school should be held as usual, be delayed or be canceled.

Regarding single-digit temperatures, Budzilek said he looks at the hour-by-hour forecast to see if the mercury will rise in the mid-morning hours. If so, school may be delayed one or two hours.

“We don't want students standing at the bus stop (in frigid temperatures,)” he said.

Myers workers have begun warming fuel in subfreezing weather to prevent it from turning to a gel form that would keep buses from starting and operating.

PennDOT alters work

The state Department of Transportation must alter the way it manages the roads during times of extremely cold weather.

Deborah L. Casadei, a spokesman with PennDOT, said salt is less effective in temperatures below 20 degrees, so PennDOT crews must treat roads with liquid magnesium chloride and anti-skid.

Casadei said while proper treatment of roads helps prevent winter accidents, it is also important for drivers to take proper safety precautions.

Aside from maintaining a safe driving speed, keeping an emergency kit is one of the most important things a driver can do in the winter.

Key items to include in the kit when facing freezing weather include a charged cell phone, a first aid kit and warm clothes.

Surprisingly, Fisher's Service and Towing doesn't see an uptick in AAA-related cold weather car trouble like it has in the past.

“People seem to be more aware,” said Chad McCall, a mechanic at Fisher's.

Drivers are more vigilant about checking their batteries in the cold, and letting their cars run a little bit each day if they don't plan to drive, he said.

Shelter gets busier

The bitter cold has a particularly harsh impact on the county's homeless population.

Bill Halle, founder of the Grace Youth and Family Foundation, said his foundation's warming shelter is expecting to see a spike in attendance early next week.

“Anytime it gets below freezing there's no way to stay warm,” Halle said. “It certainly drives people inside a lot more.”

The shelter typically serves between two and seven people each night.

Halle said the shelter, which is open to the homeless every night between 8:30 p.m. and 8:30 a.m., is considering extending its hours on Monday and Tuesday to help people facing the extreme cold.

Cold impacts your body

Just getting hit with a blast of cold air causes your blood pressure to rise.

Dr. Elliot Smith, who has an office in Evans City, said extreme temperatures create a little shock to the body and aggravate blood pressure.

That, coupled with the extra few pounds of clothing a person is wearing for winter activities, already stresses the body's system and should be considered when picking outdoor activities.

Smith said people often overestimate their activity level in winter weather.

Whether it is picking up the snow shovel or heading down the ski slope, a person should factor in his regular exercise routine, overall medical state and any medication or condition that could be a factor.

Protecting skin to avoid hypothermia also is important.

Drinking alcohol has a similar, negative, impact. It can fool the body into thinking it's warm, when in fact that person should be indoors.

Eagle staff writers John Bojarski, Will DeShong, Laurie Lindsay, Kate Malongowski, Kim Paskorz, Jared Stonesifer and Paula Grubbs contributed to this report.