That temperature is the coldest mark recorded in Philadelphia since Jan. 20, 1994, which had a low of 1 degree, according to the National Weather Service.
Record-low temperatures for the date were set, however, in Wilmington and Trenton overnight.
Wilmington’s low of 2 degrees broke the previous record of 5, set in 1978, while Trenton’s low of zero broke the old record of 6, set in 1936.
Even colder, though not record-breaking, temperatures were recorded overnight in Allentown and Reading, which had lows of minus 1, as well as Mount Pocono, where the mercury dipped to minus 10.
The weather service is calling for a high of just 17 degrees in Philadelphia.
A wind chill advisory was in effect until 11 a.m. due to winds of 15 to 20 mph, with gusts of up to 30 mph.
“Bitterly cold air combined with wind will result in dangerously cold wind chill values this morning,” the advisory says.
Code blue alerts are in effect throughout the area in an effort to get the homeless out of the extreme cold.
The cold has been blamed for at least six recent deaths in the region, with several other weather-related deaths reported in other parts of Pennsylvania and New Jersey.
SEPTA was warning riders that Regional Rail passengers could face delays due to the extreme cold. Service on the No. 11 trolley also was disrupted by downed wires, a common problem in extremely cold weather. You can get up-to-the-minute reports on Twitter by following @SEPTA.
The Cape May-Lewes Ferry has canceled all trips for Friday due to heavy ice conditions, with the first trip in each direction on Saturday also canceled.
People spending time outside are urged to cover exposed skin and take other precautions to prevent frostbite and hypothermia.
Friday night is expected to be cold as well, with overnight lows into Saturday again in the single digits. But winds will not be as strong, forecasters say.
Forecasters are expecting a wintry mix of snow and rain for Saturday afternoon and evening, creating the potential for slick travel conditions Saturday and early Sunday.
The weather service says one to three inches of snow is possible, with the potential for slightly higher amounts north and west of Philadelphia. Some ice accumulation is possible as well, the weather service said.
This week’s temperatures have been far below normal for mid-February: Typically, highs are in the mid 40s and lows are in the high 20s this time of year.