Philadelphia and its surrounding counties can expect windchill factors as low as a negative-15 by daybreak Monday, meteorologists say, as a deep freeze bears down on the region.

An arctic high pressure and air mass moving in from the north will cause temperatures to fall rapidly Sunday night into Monday morning, likely into the mid to upper single digits, with highs topping out in the mid-teens. And even though Monday will be mostly sunny, residents shouldn’t expect much of a break from the frigid weather.

Meteorologist Alex Staarmann, of the National Weather Service in Mount Holly, said windchill factors will remain below zero Monday.

“Temperatures will fall back into the lower teens Monday night, and then winds will lighten up and temperatures will start rebounding by Tuesday, and especially into Wednesday,” he said.

Philadelphia city officials had declared a code blue on Sunday, which opens all available beds in the city’s shelter system and sends 24-hour outreach teams to find people who are homeless and get them inside. Anyone who sees someone in need of shelter is asked to call the city’s homeless outreach hotline at (215) 232-1984.

Staarmann said the strong, gusty winds expected Monday could cause isolated power outages in the region.

“But the main concern is with the really cold temperatures and strong winds causing low wind chills — vulnerable people, the elderly, children, who are exposed to cold temperatures for a long period of time could start having health issues,” he said. “Frostbite, hypothermia — that’s kind of the main concern from now through Tuesday and into Wednesday.”

A pedestrian shields from the cold air as temperatures begin to drop in Rittenhouse Square Park, Philadelphia, Pa. January, 20, 2019. JOSE F. MORENO / Staff Photographer
JOSE F. MORENO / Staff Photographer
A pedestrian shields from the cold air as temperatures begin to drop in Rittenhouse Square Park, Philadelphia, Pa. January, 20, 2019. JOSE F. MORENO / Staff Photographer

The Philadelphia region was spared the snowstorm initially feared over the weekend; the storm instead tracked 20 to 30 miles north, dumping snow north of the Lehigh Valley. But Staarmann said that a freeze like Monday’s tends to last longer than the cold temperatures and strong winds that a snowstorm might have brought.

“With an arctic outbreak, the cold lasts much longer, and the longer it goes on, the more complications that can arise, especially for vulnerable people,” he said.

The cold has prompted at least one cancellation of a Martin Luther King Jr. Day event, with Rowan University in Glassboro canceling a scholarship breakfast in honor of King after administrators deemed travel conditions too hazardous. Still, Amtrak trains were expected to be back on schedule Monday after the weather forced schedule adjustments over the weekend. And in Philadelphia, Mayor Jim Kenney’s public schedule had him slated for a slew of service events Monday that are apparently going on despite the cold.