Winter has finally arrived, with frigid temperatures and more measurable snowfall expected Sunday night and Monday.

“We’re expecting there to be a pretty significant storm,” said Matthew Kramar, meteorologist with the National Weather Service in Moon.

The weather service is predicting anywhere from 2 to 5 inches of snow in the Pittsburgh region, according to its website, with high temperatures staying in the 20s through the week.

In eastern Westmoreland County, a winter storm watch goes into effect from 1 p.m. Sunday until 7 p.m. Monday. Up to 8 inches of snow could fall in the Laurel Highlands, according to the weather service website.

Kramar, though, said Saturday evening that the forecast remains fluid — with little to no snow also possible for the region and a chance of sleet or freezing rain mixed into the equation.

“It’s really a 50-50 coin flip as to which of those plays out,” he said.

The snowstorm could start as early as 7 p.m. Sunday in northern West Virginia, Kramar said, which would likely bring the storm to the Western Pennsylvania region sometime later Sunday night.

“Somewhere tomorrow evening is the most likely start time for (us) seeing some snow,” he said. “The heaviest snow is probably going to be overnight into Monday morning.”

If warmer temperatures prevail, Kramar said, Monday morning could see some ice before going back to snow for the rest of the day. Under that scenario, the Pittsburgh area could see 1 to 3 inches of snow, he said.

“If you’re heading south toward Morgantown, it will turn bad pretty quickly,” Kramar said. “Be very careful with driving safety — be prepared to delay or cancel travel plans.”

After the snow squalls Friday evening, the Pittsburgh region had received 1 to 4 inches in all, and Westmoreland County saw between 2 and 8 inches of snow, with the higher totals in the mountainous regions.

On Sunday, temperatures won’t get much higher than the low to mid-20s, Kramar said.

Monday, for now, is the tricky day to forecast.

“Temperatures could get into (the) upper 20s or lower 30s, or it could stay a little colder,” Kramar said. “It might get closer to freezing during the day on Monday, but by Monday night we should be back to cold air.”

Starting at 5 p.m. Sunday, PennDOT will implement travel restrictions for some vehicles and roadways. These restrictions mean speeds will be lowered for certain roadways and certain vehicles will be banned from roadways. Vehicles and roadways impacted include:

• Tractors without trailers

• Tractors towing unloaded or lightly loaded enclosed trailers, open trailers or tank trucks

• Tractors towing loaded tandem trailers without chains or an alternate traction device

• Enclosed or lightly loaded cargo delivery trucks and box trucks that are considered commercial motor vehicles

• Passenger vehicles towing trailers

• Recreational motor homes

• School, commercial and motor coach buses

• Motorcycles

• Interstates 70, 79 and 279, and the Pennsylvania Turnpike, including the Routes 43 and 66 extensions.

Details on restrictions can be found at pa.gov.